Pubs with rooms - of course kids can eat in the pub then.
But this would have to be, provided the kids behave themselves and don't cause any trouble or nuisance to the adults around them. And yes, I know adults can be irritating/annoying when drunk. It's a well known fact that most children get tetchy, whiny, overtired when out later than their bedtime. Some children are fine if they're allowed to stay up, as a treat.
As I said before I think here, I've seen a few pubs (not many these days to be fair) where children have been parked on seats/in high chairs, past say 7pm. And young children at this. These have been gastro pubs mostly which serve food. Atmosphere fairly friendly in all pubs, one pub is strictly an old mans pub though.
Parents sometimes do or don't engage with their DC. Kids on the whole are just being children...and I can see them getting bored, whether they have an ipad or not or colouring pens/pencils and pads. It's even worse if you factor in a child with SEN. Some of my friends brought out their 8 year old DS who has SEN to a pub about a year ago, and the poor lad was overwhelmed, bored, didn't want to talk to us (shy) and I think my DNephew was there and tried to engage with him (DNephew was then 4 or just turned 5) or he was at home with my DM, can't recall which, but this poor lad just wasn't used to it all, he has been taken out to restaurants/Harvesters and so on, but a gastro pub with people he only saw occasionally was way too much for him to take in.
Two of the local pubs I know, they have steep stairs down to the garden area. Last time I was in one of them recently, someone hadn't cleared up a drink properly when I was going into the main garden area, and I almost slipped/ tripped on the stairs where it was spilled and told one of the wait staff about it, she agreed you had to be careful on the stairs as they were very steep but wiped up the spill and apologised for it not been wiped up sooner.
She also told me there'd been a nasty accident the day before where a child had been coming out of the toilets (which are in the basement) and up into the main bar area, and then down into the main garden area, down the steep stairs, had been running ahead of it's DM, not holding hands, the DM was running behind her and trying to catch her up and call her, but had a baby strapped to her (must've just done a nappy change) and her child (about 5 the wait staff said) had gone down the stairs and tripped down the last few stairs of the steep garden stairs and cut her lip/eyebrow/forehead area/head. Ambulance was called. Luckily the DM got in touch with the pub the day after as the pub was really concerned if the child would be ok, and apparently, sadly, she had to have stitches in her head and by the side of her eyebrow area. The pub already had a trip hazard notice at the top of the stairs and the relevant hatching tape on the stairs so it's clear, but have decided since this, to put a larger, brighter notice near the stairs, so that parents are fully aware of the stair hazard. Apparently the wait staff told me, she was surprised but not really, that another patron (customer) of the pub didn't grab the running child, but realised that some people don't want to do that for fear of being accused of something else or of interfering.
Most of the local mums I know (I live in a very family friendly area) want to escape their children at night and walk the 10-15 mins up the road without them, for some well deserved adult time, without children in tow, same goes for the fathers!
Most places I've been with these mums, if we have been to a gastro pub where there have been kids/babies when we arrived, we've tended to have gone to another venue instead. We have about 7-8 pubs in the same high street area, and that's not counting numerous bars and restaurants!
If you tip these scenarios on their heads though, say you had drunk adults rocking around a soft play place... that wouldn't be nice nor appropriate for both the adults and children there, as it's a children's space, where adults take their children to play and drunk adults would be out of place, and also, hopefully they wouldn't or don't (not been to one in ages so can't comment!) sell alcohol there. It's also the 7th circle of hell for most parents... soft play.