I have to think that an “auto” option is completely feasible. So, when your “turn” comes up, and assuming there is availability and your CC works, the system buys your parking automatically.
It’s not a nice way to think about it, but probably from the seller‘s perspective, they may be missing out on upsells and therefore leaving money on the table here. It‘s possible that RU thinks the benefit of upsells is greater than the cost of pissing off customers like yourself that ONLY want it done automatically.
Not that I completely agree with the above, but at least the analysis effort is what I choose to think - that someone actually thought this all out and made an informed decision instead of winging it and pissing off people for no reason. Hard to know sometimes with RU, lol.