The reason I think this game is so popular is horse chestnut trees are very popular in the UK. For about a month each year, where I grew up the ground would be littered with conkers, both on my route to school and on school grounds. It's natural when walking around to try to find particularly large / impressive looking ones.
I have no idea why you think safety laws prevent people from playing conkers in spite of the very thread you are commenting on being evidence that people play conkers and it is perfectly legal.
Well it is banned in schools. I'm not sure how many adults you believe actually play conkers, beyond a few nutters (sic), but its mainly been banned for the people that used to actually enjoy it, kids.
I do wonder if by banning it in schools it will get less and less common till it disappears. I suppose you predictably think that's nonsense.
But pedantry aside, its banned for the people who used to play it most and enjoy it, at the place they did just that.
Conkers, bulldog, smoking behind the bike sheds (ok vaping these days), and porn (nowadays on screens rather than naughty magazines) ... a lot about British schools can be summed up in this quote:
“What exactly are you so happy about?' Harry asked her.'Oh Harry, don't you see?' Hermione breathed. 'If she could have done one thing to make absolutely sure that every single person in this school will read your interview, it was banning it!”
A quick google will get you websites of primary schools up and down this great nation with photos of their Conkers champions holding up their trophies.
As for "the law" - from a 2019 petition to make conkers legal again:
There's no law or government policy banning children from playing conkers, so we're not sure exactly what you'd like the Government or Parliament to do.
