It isn't as simple as which light is higher. The beam pattern isn't entirely flat on my MG4 Trophy: there is a 'kick up' on the nearside to illuminate the road edge, signposts and see (& unfortunately also dazzle!) pedestrians. A kick-up of some type is usual in Europe (including UK). USA types & flat beam patterns are different. MG4s (at least ones like mine) don't have the 'E' style diagonal kick-up, but a step up to a higher horizontal line. The flatness of this may be why MG called it flat beam, but on crossing the channel the higher section becomes dazzling to drivers and fails to do its job of illuminatung the roadside. The kick-up is within the pattern of each headlamp, not just that the lamp on one side is higher than the other, so you can't reverse it by raising or lowering the beam. (You might reduce how much it dazzles at the expense how far is illuminated but I doubt you could achieve legal dipping, let alone optimal safety).
The difference between the two sections of the beam is due to different angles of two pairs of LEDs and reflecors on each side. It seems to me likely that this arrangement is favoured by manufacturers so all that's needed is a small tweak somewhere to change which side is higher, rather than needing to make different types of light for different countries. However, the obvious adjustment screws act on the whole light assembly and don't change each pair separately.
Some cars, especially ones with dazzly bluish bright HID lamps, have a left/right dipping adjustment for driving on the left/right, and some do have flat beams with no kick-up that are suitable either side of the road IF correctly adjusted, but without either of these aids, carefully placed beam deflectors or blockers to remove the kick-up are essential (black tape works). The kick-up is very helpful and safer when on the on the correct side (but not required); on the wrong side it's dazzling, unsafe, illegal and could land you in trouble with the law as well as with other drivers.
If changing the relatve angles / heights of each pair is reasonably practical, then setting them at equal angles woud make the pattern flat for regular cross-channel commuters, and changing over which is higher would suit well for a long time the other side. However, for shortish trips, it's easy to use tape to cover the relevant part of the light to remove the kick-up. It's the centre pair of lamps on each side; when it isn't too bright and sunny, with dip beams pointing to a pale wall or door to see the effect, cover the top part of where the centre pair of lights shines through illuminating the outer clear plastic: the right area is nicely obvious if the lights aren't perfectly clean! Observe the effect on the wall to ensure you obscure all of the kick-up, leaving an horizontal top that matches the line of the outer pair of lamps. Then enjoy travelling.
