Lance trailer “flat roof” makes roof water ponds -- problems

Travel trailers have had flat roofs for years. It makes little difference if it leaks in from a puddle or from just rain. Cities everywhere have flat roof buildings and have forever. The cure of course is maintenance. maintenance, maintenance.
I'm sure trailer manufactures figure the trailer will be perfectly level one time and tipped one way or the other next time it's parked, so they just don't worry about it much.
Yes, it seems better to have a little slope to it but it's not a deal breaker for me.