If I see my burger bleed, I'm sending it back, because I don't want food poisoning. Not sure how they came up with this nonsense that they think people want to see bloody under cooked ground meat.
it’s not blood, “it's myoglobin, the protein that delivers oxygen to an animal's muscles. This protein turns red when meat is cut, or exposed to air. Heating the protein turns it a darker color. Rare meat isn't “bloody,” it is just cooked to a lower temperature” [0]
you’re sending stuff back based on your lack of knowledge.
[0] https://www.google.co.uk/amp/s/www.huffpost.com/entry/what-i...
Calling it "blood" is wrong (but everybody knows what that means), but sending it back for more cooking isn't.
Some people think the risk is small enough that they're not bothered by it.