Counterpoint: do restaurant customers (i.e. ordinary people) also think these websites are awful? When I see a website like that, I just think "it's not targeting me". Also, I've actually given up on all websites of non-internet companies, including big retailers. It's just too tedious to find information, too slow loading. Their mobile sites often load quicker. but have even less info. You're better off ringing them…
I notice that regular customers mostly use Yelp, OpenTable or just plain Google to look up a restaurant's phone number or location. That suggests to me that they've learned that going to the actual web site is usually a bad bet.