My understanding was that he wrote an effective program and wasn't allowed to use it for homework and tests.

On reading that line, I thought about what I would have done if I had been in the teacher's position. I thought: well, he clearly understands the bits that the assigned homework was to reinforce, why not excuse him from that drudgery? Better yet, give him additional problems to apply his program to that expose issues with circuit simulators, giving him a deeper understanding. But then: that is time I am spending as a teacher that benefits him only, not the rest of the class (my time as a teacher is finite). Is that fair? And: what would happen if other students/parents found out about this arrangement - wouldn't there be complaints? Of course, what he's getting at is that the educational process should be designed to avoid conflicts like these...

That's a function of available resources.

With more resources for teaching it would be perfectly possible for schools to look for individual talent and work to develop it.

Supposedly the better private - public in the UK - schools try to do this already. With fees as they are, they certainly have the resources for it.

I know someone who went through public school and was in a music class of exactly two pupils. The school also worked hard to provide relevant professional contacts.

So with someone talented, a teacher wouldn't be thinking about limited time, but about whether there were any local startups/companies who might want an intern.

It's not disrespect by the teachers, so much as disrespect by a political system that tries to limit these kinds of opportunity to a tiny fraction of the population.