One of the most annoying things to me is not being allowed to dine alone, lonely or not. Many korean bbq restaurants explicitly require 2 or more people to permit you to dine in, which is annoying as fuck.
It's just really frustrating that there are entire classes of restaurants I can't eat at while on business trip or similar. They will not even just charge me an additional fee or charge me for 2 people (I've asked, and I know how it works/don't need handholding or explanations so they really just need to drop off the meat twice and change the grill once if it's too burnt), just typically get "no we can't do that, minimum 2 people" in response