Will anybody really ever come by to pick up Perseverence's samples?
That has struck me as really implausible. If it could carry the sample containers to wherever it fills them, it could carry them to wherever it ends up, too, and whatever is supposed to fetch them could make a single stop. Sending another lander just to sweep up after it seems massively wasteful.
Sending a lander to pick up the samples is worth it just for the technical aspect.
Making a successful return trip would be an important milestone, we never did anything close to that before. Yes, moon landings, but the moon is 100-1000 times closer and 10 times less massive than mars, with half its surface gravity.
If it ever happens, the "get back samples" mission is likely to focus on that technical aspect more than anything else, it may not even have a way to explore and collect samples. So let Perseverance do the collection because it is what it is designed for and put them in a neat pile so that the other mission can focus on getting them back.
Further missions should be able to do both collection and return, maybe even take people, but starting small may be a good idea, especially if human lives are at stake.
I get what you're saying. It's ineffective to robotically collect them this way (ever), and if humans go collect them, they could just collect a lot more while they're there, making it all pointless.
Perhaps an answer is that one of the contingencies being covered by the Perseverance sample-collecting is against future contamination? Maybe the NASA missions have been extraordinarily careful about not contaminating Mars with earth microbes, but they're worried that future commercial crewed missions won't be able to be so careful. Then when the humans get there, they'll have some unspoiled sample containers to experiment on and compare to the post-human samples.
Perseverance will take samples from a variety of locations, and cache them in one location for pickup. The pickup mission won't need to drive around the surface for a year with drilling equipment.
That was not the description I read in official materials: that said the plan was to leave the sample containers on the track. It can't be both, and there can't be any uncertainty. Did they change plans?
Clue?