Well, there are of course structural differences. Not much in terms of general aviation, nearly no regional airlines, the smallest type that is commercially viable is either a 737 or an a320, everything else would have to be cross financed by someone, and that is not going to happen, especially with a low cost sector that is much bigger than in the US, where it hovers around 25% of the market, while it is around 35 to 40% in Europe without any signs of stopping in growth.
And of course, since we haven't used paper cheques in more than 30 years, there wasn't any night freight business in small planes to fly useless pieces of papers around the continent.
Not to mention, airlines have been hiring cadets since WWII, trained them themselves, eventually outsourcing those schools and therefore are very comfortable with that. And yes, that was lead by airlines like Lufthansa, British Airways and Air France, not to mention the smaller ones like KLM, Swissair and Swiss as well as Austrian and the Sabena when it still existed. In fact, the MPL, which allows cadets with just 50 hours of experience to fly A320s on the line, was mainly developed by Lufthansa.
And of course, it is quite a diverse continent, with differing labor laws in each of the many tiny countries, different languages, wildly differing income levels and so on. In fact, even in Germany the average income per year is just over 38.000€, and being able to earn in excess of 170k after just 5 years out of flightschool piloting an A320 for a kinda smallish airlines (just 300+ A320 family aircraft growing by roughly 8% each year while turning a profit for 20 years running) is not a bad deal at all. Especially considering that the average yearly salary within the same union can be as low as 9000€ (romania).
And of course, there is unionization. But it doesn't necessarily help. Lufthansa mainline pilots went on strike 14 times in their last dispute. In the end they signed a contract that lowered their T&Cs by 15% on average. That has been just a year ago, amid record profits of their company.