Before getting pregnant, I was one of those people who would grumble if I happen to be anywhere public - like a restaurant or cafeteria - which features a screaming baby/toddler. "This is no place for a child. Why don't they get someone to babysit? Or check in advance whether it is a child-friendly environment?" I'd say to whoever happens to be with me.
I'm sure the majority - or at least, a fair number - would have checked in advance - had they had the opportunity to do so. I have yet to see on a website any mention of whether the restaurant/cafe' is child-friendly or not [excluding places such as McDonald's/Burger King where one takes these things for granted]. Making a "quick phone call" might be the last thing the parent[s] find time for - considering how demanding children can be, and how many things said parent needs to remember to juggle. Also, sometimes, you just want to go some place with the child. Or, a baby sitter is not an option [due to lack of contacts/funds/pick-up and drop-off arrangements].
You don't really look out for ramps that will make entrance with a pushchair/pram easier, or baby changers, or high chairs, unless you're either pregnant, or have children of your own. I've been trying to keep track of which places have the aforementioned facilities, and which don't. Needless to say, I'm failing as I have become rather forgetful. Perhaps, I should start writing these things down [if I remember].
My suggestion to the catering/entertainment establishments is this:
Put it in writing. Any child-related facilities existing in your establishment should be promoted on your websites. It will be good for business - both in setting all customers' expectations, as well as attracting new business.
Bottom line? Simple. Help us help you.