Spoken clearly by someone who lacks experience with having children.
Look, it works pretty simple. Witching hour is right before dinner time. Kids are grumpy / hangry (hungry + angry). On top of that, young children have a short attention span and patience. Children certainly can socialize (after toddler age), but while sitting still at a restaurant table? Not for long. A tablet or smartphone is a tool to keep them distracted during waiting. Heck, playing is learning too, so it is IMO a learning tool.
That said, I can recommend a family restaurant.
For example, on vacation to Texel we went to this one [1]. I have not even seen the indoor playground (only outdoor) as the two times we were here the weather was great. Tons of children playing, the picture you see of the outdoor playground is not even 20% of the whole playground. It is quite large, with a special area for toddlers.
Moreover, we went to a family friendly bungalow park with activities for children, and the restaurant on the park (we didn't go to it this year but previous year) has an adjacent playground. If you're on a more tight budget, the same exists for camping.
Do children socialize on playgrounds? Toddlers kind of don't. They're still in their own world, at best they play 'parallel'. After toddler age? Absolutely. They form new bonds, become friends, they play together. They also get into conflict with each other, which forces them to learn conflict solving skills. They practice motor skills and build muscles. But I couldn't leave them completely alone, so I stayed in the vicinity. Hence, I did not socialize (which, as autistic as I am, I do not mind :P).
On top of that, I remember going to McDonald's as kid in the late 80s (it was one of the first McD's in my country) and they had a playground with balls in it. Also great fun. For the record: I did have a Nintendo game watch and Game Boy back then. But in the McD's such wasn't necessary.
And finally, to all those people who claim they want to socialize with strangers they visually meet. Yeah, that is why people sat on banks reading newspapers, why walkman and discman existed long ago already, why the hairdresser has magazines, why trains have a silent area where you can read a book, etc. Let's face it: not everyone is an extrovert.
[1] https://www.catharinahoeve-texel.nl/kids