We grew up taping tennis balls. I think Insulation tape over tennis balls was invented right here in the 70's.
We don't have quick bowlers because 90% of our kids don't try and bowl fast, they attempt to bowl accurately first.
In my day every school (more than 20 decent high schools) had guys trying to bowl as fast as they could, you don't see that much anymore.
What little school cricket we play is T20. You have to get through the overs- shortened run up, you have to be accurate and pace off works. It's not conducive to bowling fast.
It's less to do with scouting and youth development and more to do with competitive school cricket and boys trying to be the fastest in the country and getting selected for age group sides. Guys wanted a reputation of being quick.
We've got some tall athletic guys in our men's cricket and I'm willing to bet they could bowl faster than they do, but they've spent so long bowling within themselves that they have zero control when they try and crank it up.
Plus it's tiring
We've got very few guys that bowl over a stiff leading leg and most have poor wrists. That's 10-15kph right there.
Most don't run in either, they amble. That's another 5 kph.
That's coaching, or lack thereof.
I once watched a coach showing a really promising young guy painstakingly teaching him to bowl with no wrist flex so he could be more accurate. Mind boggling. I spoke to the parent, but he wouldn't change because that coach could get his son into the team.