A tax on horsepower isn't logical, reasonable or justifiable - most people are rarely deploying maximum horsepower anyway (if they're driving legally) - and as with any tax based system, it means its fine for rich people, even if they're utter pricks behind the wheel.
However, and I've said this for decades - licenses should be graduated in steps by performance. Most people would be fine on a <170hp <2t (or less) license, the more powerful you get, the more tests you have to take.
There's no issue with people having powerful cars, until they start driving them like absolute nobs with no consideration to their surroundings or other road users. We have categories on our licenses based on number of axles and loading, seems daft that you can step out of a FWD base Corsa and into a 1000hp+ car with little more than 12 hours experience driving at all (on <70mph dual carriageway or less, roads during the day), just as it's daft I could have driven a rigid lorry towing a trailer after only ever driving a 3 door Corsa B.