No protection scheme, BUT games designed for PAL machines wouldn't work on NTSC machines (and some games designed specifically for NTSC wouldnt work on PAL Amigas either)
Since the games were programed relying heavily on the sync of the video chip's clock rate(or something like that, I'm not a big techie
), PAL games would just fuckup on NTSC machines beacuse of the different clock. Some games worked fine on both machiens, usually those that you play on your PAL meega and leave a 56 pixels border below the screen.
On the C64 same stuff happened. But no specific country lockup.