At one stage Panasonic/Matsu****a were actually a bit devious: they were legally obliged to only sell the drives locked in Europe, but then posted firmware upgrades on their website which rendered the drives "free"
However somewhere along the line they got threatened by the law and had to pull back from doing this
As far as I'm aware the other big manufacturer groups played things straight and never officially released any patches to do this - but some leaked unofficially. In some cases it was possible to flash one drive as another: e.g. there were occasions where it was possible to flash a locked Sony drive with the firmware from a differently branded (e.g. LG) but otherwise identical Optiarc product...... You could sometimes do the same with the TSS Samsung-Toshiba group products.
However, unless you knew for sure, it was a good way of turning a drive into a brick. There are specialists sites devoted to this kind of thing
Of course, theres more than just the drive to worry about - the playback software also has to be region-free friendly, some of it isn't