I think there's a world of difference between shoe choice and being left at preschool.
To us, it's 2.5 hours - to a child who's not been left with anyone but close family - or at all - it's a totally alien experience.
DS1 was 2.9 when he went and there's a thread somewhere detailing the traumatic start he had there.
He had a couple of sessions where I left but his auntie or grandmother stayed (my nephew also goes to the same preschool). Then he had one session where I left (he was fine, kissed me goodbye, etc - he's used to being left as I work, but he gets left with my mum and dad or DH's mum and dad - he'd never been left in a room of strangers before. He loves his toddler group, but he always had an adult he knew with him there). Half an hour or so later the (lovely and kind) leader rang and said he was utterly inconsolable - did I want them to keep trying to cheer him up or did I want to come and get him?
Of course, I went straight to get him. He was being carried round by the leader, they'd been trying to distract him with puzzles, toys, etc - but he was sobbing and saying, "Oh, dear, oh, dear, oh, dear" over and over again.
I could have left him. I could've repeated this over and over and maybe he'd have settled in time. But I couldn't - he was beside himself. He didn't have the depth of understanding to realise what was going on - as adults we know what preschool is, we know they're going to school next, we know about teachers and all that malarkey.
But when you're not even three, you don't know that stuff. Even if you are told about it, you don't really understand.
So someone (me or his grandmother) stayed with him until he was happy to be left. He loves it now - it took about a term for him to be totally comfortable there, but he races in and doesn't bat an eyelid when I leave him now.
Maybe he'd have been the same if I'd left him to get on with it, but it would have been very hard on us both. It really isn't comparable with which colour beaker issues. I don't bugger about with stuff like that. We have "one chance then change the subject" - so "I want the red beaker! No, I want the green beaker!" "One chance - which one?" "Red!" "OK, here's the red beaker" "No, green!" "You said red, that's the end of it, now we're changing the subject"
I have very, very clear memories of preschool. I didn't really like it - I was happy pottering about at home and was a quiet, well-behaved toddler with no excess boister to get rid of. I was scared of the boys on trikes and I didn't know how to make friends - being at preschool didn't change that. Heck, being at SCHOOL didn't change that particularly!
However, even though I went to preschool from 2.2 and school from 4.3, I could read before I started school - and was learning to write too