It's not just your imagination.

Sometimes friends are surprised to learn that we don't ever use the metric system in USA. ("You measure flour in cups? That's so cute!" "Why did you have to learn Celsius for Chem lab?") Though a reminder that their road distances are in miles generally helps.

Recently I've been thinking about fluid measures.

I'm pretty sure that pubs give 'real' pints, ie. 16 ounces. 500 mL = 16.9 oz, so if it's actually a half-litre of beer you're buying you'd be getting slightly more.
You have to be careful, though, 1 imperial pint (used in the UK) = 1.2 US pints = 568 mL

A shot is measured as 25 mL, which is 0.85 oz.. I'm pretty sure the US definition of a shot is 1 ounce.

But what really sparked this thought are cans of soda. I don't usually buy soda here because it's kind of a rip-off, but here and there I will. One can is 330 mL, and by the time I finish it I think "hmm, that didn't seem like as much as I remember."
330 mL is about 11.1 oz.