I would only power it when there is a car on top of it. That was done a hundred years ago. Now it is much easier. It just takes an IGBT per section. Seems pretty easy.
Magnetic Resonate wireless chargers are about 90% efficient but it seems that is a lot more complicated and expensive. Still this seems like an huge improvement over those charging stations.
I don’t see any reason to charge from the top of the vehicle no matter what method you use.
Charging from the top means you can easily keep the public away from the contacts. It’s also easier to keep things clean. It might also be a factor that you don’t have to dig up the road to add a new station/charger.
There was likely some cost/benefit analysis done that found it was cheaper/more reliable/less logistically complex.
