If the aliens are as smart as some claim they are why do they keep wrecking their saucermobiles? And if they are really very smart they would have checked in with me. Might have saved them a wreck or two?
That question nags at me too. Here’s what I think:
1) You’re correct in a way. Their equipment must be susceptible to our atmosphere in some way, or it just plain sux. Sucky equipment won’t stand up in space at all - ever. So, I stick with something atmospheric.
B) There are so many alien or UAV/UFOs swirling around the atmosphere that by numbers alone there will be accidents.
III) I have another idea that stems from Uncle Clif. This hypothesis suggests the aliens STOLE or “acquired” the tech, but don’t really know how to use it well. Therein, all the crashes.
They are illegal Aliens.
I would guess agency craft retrieval teams would use a cover story.