I am sure this will garner some debate ... but for whatever it's worth ... the majority of people are right-handed, and right-handed males will therefore typically 'dress left' (since they have to choose, they will position their cock inside their underwear down/towards the left pant leg). The left-handed ones typically 'dress right'. Of course, this is not universal and there are always exceptions, as you can read in previous posts.
A tailor, creating a bespoke suit for a man, will take into account all variabilities, such as one hip being higher than the opposite, one arm being longer than the opposite, on leg being longer than the opposite. It is why a truly custom made suit costs what it does. The tailor observes if you are left or right-handed, and adjusts the pant legs accordingly, after confirming his observation by asking you which way you dress.
Note that this preference applies to bathing suits, shorts, jocks etc. too.
At one time, the manufacturers of jeans and other trousers actually accounted for this by cutting the trouser pattern assuming that most guys were right handed, and therefore needed more material in the left pant leg. Not sure if this is still done, but it makes sense. Of course, since today's fashion is ultra loose, over-sized and falling half off the ass, maybe this all becomes somewhat academic. Or if your culture does not include pants / leggings as typical male attire (i.e. kilts / sarongs).