I believe there is a huge cultural difference especially between the USA and most of Europe. European airlines were basically forced to run their own flight schools for a long time, as there is not a big GA sector and after WW2 there was a lost generation. And yes, that is ancient history but of course led to the european norm of having pilots trained directly into airline flight decks.
And of course there is much to be said about structured and focused training, the military has done that pretty much forever. Of course there are differences between civil and military training, as the „mission profile“ is very much different.
Having flown with MPL cadets as well as former MPL now captains i did not see a marked difference between them, the „normal“ abinitio CPL/ATPL holders or those having worked their way up outside that structured training route, except that the latter sometimes had more of a problem with SOP centered operation.
I have to say that training changed for the better in recent years with first ATQP and then the change over to EBT, much more relevant training can be done in the valuable time in the box that way.