Am I missing something in the pricing or is the Storage costs very unappealing

Yes, there's no comparison on the IOPs or anything else and what counts as storage. They all count slightly differently and so unless you account for it all it's a bit moot.

AWS alone has different tiers of storage from HDD to NVME ssd. The pricing varies greatly.

RDS will literally count anything including temporary files as usage of storage. Planetscale claims not to.