Carrot flies do tend to stay close to the ground, but of course, can get higher if the wind gets up!
I've actually seen one trying to get through a net on the ground, and it was a determined blighter, so we grow short carrots in holed buckets with the tops about 2'6" above ground (on a shelf). This has been the norm here for several years, and apart from a little slug damage, it seems to work.
The seed is just broadcast over the top of the compost and dusted in, and apart from watering (they are in trays), the carrots grow densely, and so far have no sign of flies.
There's another post somewhere here, where an experienced poster does something similar, but in a raised bed - but I can't find it...
So you weren't dreaming after all:0)