Aren’t all BMX bikes the same size?

Being a child of the 80s and riding the wave of the BMX bandit era, it is true that then most BMX bikes were basically the same size, with kids racing whatever they could get there hands on and size specific race bikes being exotic American manufactured frames and smaller parts coming out of small boutique fabrication companies. But as the sport progressed and BMX race bike sizing became more standardised, we are now at a point where there’s bike size specific to fit kids from 3 years old, up to the point they are fully grown. From Micro Minis with 18 inch wheels, the Pro XXXLs (and bigger). Then there are the 24 inch cruiser race bikes