Some racers use a reverse (opposite of street standard) shift pattern so they can more easily upshift while finishing a turn. With standard shift, they might not be able to get their toe between the road and the lever. Not all racers use this pattern. Mat Mladin supposedly uses a standard shift pattern.
Manufacturers use a standardized pattern. I'm not sure if that came about because of an industry wide agreement or if there was some government legislation involved at some point. The effect is the same -- they are all the same. I have no idea why it is 1st gear is down and all other gears are up. Probably arbitrary.
On most bikes it is easy to switch the pattern if you want. Just reverse the stock linkage. Or if that won't work, aftermarket rearsets almost always allow the pattern to be reversed.
I used to ride and race Nortons years ago. The gear shift lever was on the right side and the shift pattern was one up, three down. I believe there was legislation in the early 70's that standardized the shift lever to be on the left side and a one down, then up, up, up for up shifting. Norton actually changed their shift lever to the other side just before they went out of business. I personally thought the up, down pattern to be better for racing since you finish with all your down shifting just before a turn then its easy to upshift coming out of turns by pushing down on the shift lever.
Yeas, I haven't raced, but the up, down down down system seems more logical. I recall somewhere that the shift from right-hand to left-hand shifting came about due to US regs? Something about being able to lean on your 'more sure' right foot (most people being right-handed) while putting it into gear??
As to the down up up up - can't imagine that any laws would have been enacted on that one... but guess it's too late for manufacturers to change now
Early 70's Ducatis were right foot change aswell. I had a '76 900 SS that looked like a stop gap measure with the introduction of left foot changes as it had a linkage going from the left hand side through the back of the engine to the right hand side with more linkages then into the right side crankcase. I think it was more of a case of Japanese manufacturers selling more bikes and the left foot change was the standard for them...maybe due to the architecture of the engine and drivetrain more than any sort of cultural difference.