Rey grew up as some sort of indentured laborer making a living from scrap. I could maybe see her picking up enough piloting skills to re-park or transport vehicles around the lot under close supervision, but I don’t really buy her employer giving her the freedom to just go hot-dogging across the galaxy, or zooming through canyons.
Finn says he works in “sanitation” . While perhaps this is just punishment, or maybe all stormtroopers have second jobs because the First Order can’t afford contract laborers, it still doesn’t lend itself towards having a lot of extensive training in melee combat as a shock trooper.