Do you expect your meal to be paid if you’re invited to a dinner

It was my younger sister’s (16) birthday and my sister invited her friend at last minute to eat with my parents. They went out to eat and the friend ordered a $50 steak while my parents went for the $20 range. My mother was pissed because she thought the friend went over. My mother didn’t say anything to girl but thought it was in poor taste to do it. Personally when I’m invited I expect to pay and always go the price range everyone goes for to make it easier. What do y’all think?

Bonus question: if your meal is paid for do you order within everyone’s price range or pick whatever you want.