[ff317]

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.