grandMattie
As a poor young married, I went out to dinner with the wives of DH’s colleagues. I picked modestly priced main and pudding and only drank water (which is what I could afford). The wife of one of the managers had three courses including lobster, and had quite a lot to drink. To my horror, the bill was then divided equally! I had to pay so much more than I could afford. I never went out with them again.
Since then, I have made sure that the bill is paid according to what you have consumed yourself.
I had a very similar experience in my student days.
Since then, I always when asked out, or asking others out, discuss who is paying, and I have always refused to divide the entire bill by the number of diners, as I have no wish to dictate that others stick to the cheapest items on the menu, nor to pay a greater amount than I can afford.