First off, I think this is a bad business decision.

But

>Even if the only vegetarian option is fries, which is not uncommon.

Is not true in my experience.

I'm a vegetarian and I only very rarely have problems finding something to eat at restaurants, and not fries, I don't even like fries. Though sometimes I have to ask for substitutions.

I admit, if you are not actually open to eating non-meat products you'd have issues.