Even an average FPV pilot can wreck infantry out in the open, the better pilots will make multiple dives before committing to a good angle/direct impact. You can’t outrun a drone, REBs don’t cover all frequencies, and shooting them down is hard.
Yep, they didn't have shit like this when I was in, but it's the same as artillery or rocket barrages. If you're caught in an open field, there's no point in running. You're either getting hit or you're not. Running is just as likely to take you out of a safe spot and put you directly in the line of fire. Just lay down and wait it out.
What sort of field has absolutely no cover anywhere for 100s of meters and is attacked such that everywhere around you in like 500 meter radius is equally getting hit?