Or they know better than to obsess about it. As people actually playing the game won't be looking that closely at the tracks anyway.
Exactly. Most all games have this kindof stuff. Devs don't have time to fuss over every little detail, they are typically on tight schedules and budgets and have TONS of work to do.
So I think they are completely 'professional' as that's how the professionals do it.
However hobbiests usually have as much time to devote to their maps as they wish (contests would be the rare exception to the rule).
It's the same with their models. I used to try and get all textures on my models perfectly aligned and whatnot. But look at alot of Valve props.
The soldiers rockets (same a sentries) have some really bad tex stretching, the first alpine trees had some horrible spots...
But only mappers or modelers notice. Everyone else is to engulfed in the game, killing and trying not to die to notice or care.