Technically there's no great difference between EASA, FAA or any other country's APTL. Perhaps AirLaw and Flight Time Limitations one can find the most differences.
One should not require to take the full package of exams.
Politically the issue takes it to a level where protectionism comes into play, requiring us to take the full package.
Fair or not these are the rules most countries follow.
But hey, even within EASA countries one has to change its EASA licence to a EASA issued licence of the country you're flying in.
A UK EASA licence is not quite the same as a German EASA licence.
So, maybe EASA should start by resolving this within EASA countries and then who knows, things could become easier.