Why is there cow cheese but no pig cheese?

There are several main reasons, historically:

1. Cows, sheep and goats have udders, and can be milked by hand into a bucket. Pigs (or cats, or humans for that matter) have nipples, where you need to suck the milk out. Consider that most of the cheese in the world was invented before machinery was able to create a vacuum, this means that the only option would have been to suck milk from the pig and spit it into the bucket.
2. For making cheese, the fat/protein ratio in the milk is important. It changes, obviously, from species to species, which is why there aren't many hard yellow cheeses made of goat's milk.

Lastly, I have actually had camel's milk ice-cream, which goes to show that it's just a cultural thing mostly.

It's possible, but the reason why we drink cow/goat/sheep milk is because of how much easier it is to get at it. Pigs don't store their milk in udders, making each milking of them a very low-yield process.

As daniel suggests, cost of production is the main issue.

But it is possible. In fact, recently in the UK a restaurant served human breast milk ice cream [Source] and I don't see any reason why we couldn't have cheeses made from human milk.

There are even cheeses* that are made without any milk for vegans [Source], and it sounds absolutely delicious

Vegan cheeses are made from ingredients such as soya protein and vegetable oil

*Not real cheese, keep it well away from my pizza

I think point 1 in Carmi's answer is largely the explanation but I thought I'd add to it with some data I found in a recent article.

The AV Club (of all places) released an article in 2016 titled "Why don't we drink pigs milk?" While this question is about cheese, milk is first required for cheese to happen, so if there's difficulty in obtaining a supply of milk, one can't make cheese. So, from the article, we find that milking a pig is quite complex, from an anatomical angle.

There haven’t been machines manufactured that would efficiently milk a sow’s 14 teats.

They're also quite small by comparison. Supply wise, these teats give off (all together) much less milk.

And what milk could be produced is paltry by comparison: A sow produces one-fifth the milk of a cow.

Additionally, while a cow can get pregnant while lactating, a pig can not.

Maxwell also said the hog industry’s objective is to produce as many pigs as possible (sows give birth to roughly two dozen piglets annually)—and a sow can’t get pregnant while she’s lactating.

Even if you get past or ignore these concerns, getting a pig to cooperate with your milking contraption will likely be complicated.

Maxwell said when they obtain milk samples from sows, the animal has to be lying down. “I don’t know how difficult it would be to milk the sow standing up,” he said. “But it would be another learning curve that would potentially be difficult to overcome. It’s not a feasible scenario.”

Not that that’s stopped some people from trying. Edward Lee, the James Beard Award-nominated chef of 610 Magnolia, was so intrigued with serving pig’s milk cheese at his Louisville, Kentucky, restaurant that he experimented with different ways of milking a pig. The most extreme involved ingratiating himself to the sow by smearing pig poop on his jacket and sitting near her until she was familiar enough with him to fall asleep. Then he’d move in to milk—but even this was to no avail. In the end, as Lee told Modern Farmer, “Cows have been domesticated for so many years, they’re very docile. You get within 15 feet of a sow, she’ll get up on her hind legs and get defensive. She might charge you. And once she charges you, just forget it. She’s already identified you as an enemy.”

Lee added, “Goats don’t like to be milked either. But if you get kicked by a goat, you’ll get bruised. Get hit by a 250-pound sow, you’re dead. There’s a very basic practical reason people don’t attempt it. No one else is crazy enough to get in the barn with ’em.”

So, unless we discover it to be an elixir of life that everyone wants (and are willing to give up bacon for it), it seems unlikely that we'll see pig milk - or cheese - in the near future.

Another explanation is diet. Pigs eat pretty much anything, while cows are rather selective about the grass they eat. The milk takes on a lot of the characteristics of the food the animal eats, so cheese made from a pig would probably be pretty bad.

I'm a cheese monger in the Pacific Northwest of the U.S.A. (PNW), and I've heard of a pigs milk cheese that is produced in Italy.

Some reports say that it's produced in or around Tuscany. The cheese is called Porcino (Italian for "something of the pig" - I may have the spelling wrong) and is rarely sold outside the region, and never outside of Italy.

One website that talked about Porcino cited an article on it, but later said that the article was a hoax. I have no way to confirm or deny the validity of the article. Though I have talked to cheese distributors here in the PNW, and they confirm that it is a real cheese, but that there is no way for them to procure it for sale in this part of the world.

According to my sources, some of the same Italian families have been making this cheese for over a millennium.

I think we are also neglecting the production costs of making pig's milk cheese. Given the amount of milk that would be needed to turn a profit or even make a single wheel compared to the amount of care and cost associated with raising and maintaining a sow for milk (which from what I understand does not produce a great deal of milk anyway) isn't very economical.

You cannot make cheese from human milk. Everyone who has tried has mixed human milk with cow's milk. The have tried but failed to make cheese from purely human milk.

What they do not seem to realize is when they separate the curd from the whey, every single ounce of human milk is discarded in the whey. Human milk does not form curds - period. You cannot make cheese without curds.

cheese or butter can not be made from pig camel horse milk its just not possible it will not turn in to cheese only cow sheep and goat milk can be made into cheese