Slightly differing order
1. Europe is not dependant upon GA for its supply of pilots. The US is. That is comparing apples and oranges and cannot be done in a paragraph or two. To compare the two theories is irrelevent. Ab initio may be the norm on your side, but not here The path to the right seat would change fundementally if GA is heavily burdened.
2. Paying to be a controller. Beyond my perview. Reminds me of the Comair academy you mentioned, pay for training.
3. Can't speak to Jet Blue, as they are a new company with little history, promising however. SouthWest on the other hand I can as my airline competes against them in many venues. They are profitable for a number of reasons, too many to list. They all lead to the basic building blocks at the base of the pyramid. I promise you if even they were burdened with a 10% tax as you suggest, they would lose pax. We often dont compete against each other, we compete against the car. SW has a number of city pairs that compete directly with a chevy. The ability to drive there in a reasonable period of time vs the crowds of an airport, security hassles, wait time, and all the other joys of flying. Now add in 10 % and the decision is made for a family of four or five now must now pay a much larger percentage. The US culture is based largely on automobiles, Fair to say Europe less so.
4. As to safety. Its not like we dont have pilots scud running now.
Add in added costs and that number will increase. To say that they shouldn't be pilots is a nice pie in the sky observation, but it misses the fact that they are already flying. It is happening as we speak. You think tacking additional costs wont change things? Unless the FAA puts inspectors beyond every rotating beacon its gonna happen.