cost versus benefit on temporary covers.....you still need to drain the water away once you've created a quarter mile bathtub.....I am sure some new tracks have better water run-off management than the older tracks....drainage ditch-like depressions either side of retaining wall etc....might help, but it's not a turf surface that gets saturated, it's asphalt which can take a bit of a blow-dry without hurting....so, I'm guessing it's the cost of it versus just how much it helps in the end....
stadiums have been discussed since I can remember....a permanent structure costs too much (at least until this sport becomes as popular as football), but in order to keep tracks in proximity to the giant markets the NHRA is trying to tap into, it might be the only way it might survive 50 more years....not so much for waterproofing (it's a bonus) but more for sound abatement...
replace blimp with suspended cameras for that overhead view, though it adds the unique view, it does little for me enjoying the racing....