I think it stands to reason that if computing folder sizes was a trivial thing to implement the Drive folks would've done it by now. It's obviously useful.
It equally stands to reason that by not offering this feature, they make it more difficult for users to manage their quota, which means they can drive folks to higher-priced plans. This would be the "malice" take.
Given Google's history with UX and support of existing products, the other possibility is the product is simply understaffed/undermaintained and poorly managed. This is the "incompetence" take.
And again, to emphasize: rclone can do this today. Is it a bit slow (and possibly limited)? Absolutely. But it works, and is how I've turned to managing my own gdrive quota since Google seems to be either unwilling or incapable of offering the functionality themselves.
I disagree - rclone can solve a substantially simpler and different problem (i.e. computing the size of a specified hierarchy on-demand). Being able to store and produce sizes of arbitrary folders in Drive for however many millions of users in a reasonable time frame is a substantially more challenging problem, and what we're talking about here. Google probably hasn't provided the on-demand version of this because it's trivial to script with their API.
Given that Google does offer you tools for managing your quota, and knowing it's a very difficult problem to solve, I'm disinclined to believe this is malicious or incompetent.
Given Google's history with UX and support of existing products, the other possibility is the product is simply understaffed/undermaintained and poorly managed. This is the "incompetence" take.
And again, to emphasize: rclone can do this today. Is it a bit slow (and possibly limited)? Absolutely. But it works, and is how I've turned to managing my own gdrive quota since Google seems to be either unwilling or incapable of offering the functionality themselves.