Why do we start reading etc so early in UK?

[Cortina]

Speaking to American and European friends all are shocked and think we are bonkers to start the formal stuff so young.
Beginning to get down to the serious business of reading and writing seems to happen when their children are rising 7.

Apparently Finnish grade 4 children have the highest average reading age internationally - and they don't start until 7.

Appreciate this is going to change any time soon but wonder why have a different philosophy/system in the UK. I have no idea why.

Ah ok, thanks Cory!

(Feel like I ought to contribute something solid to the discussion but I have no idea. Sad though if 4 year olds are made to feel a failure especially since it shouldn't really matter what age someone learns to read. I mean, it's not like anyone ever asks you as a grown up at what age you learnt to read, or something that you need to put on a CV: "She learnt to read at 3.5 yrs? Yep, she definitely sounds the best candidate for the job then...")