We could have a philosophical debate regarding the Euro v. US approach to these things.
Over here, there is a strict
initial medical, whose purpose is (presumably) to weed out as much dead wood (I am doing my best WW2 RAF-speak here; may need assistance) as possible. After that, it is a lot easier and in addition you can hang in there on the basis of demonstrated ability. But if you fail the initial, you are out, finished, and for ever not good enough. Even though you could do the
renewal medical the very next day and pass that - but you are the same person
Silly isn't it. So you get weird things going on, like JAA ATPL candidates going to various JAA countries (not the UK, I dare say) to get their initial vision test done.
In the USA the Class 1 initial is the same as the renewal. Perfectly logical IMHO. Demonstrated ability available too.