That data is used in some alarmingly manipulative ways that directly affect your life.
I'm generally a pretty frugal person, I have a good handle on my personal finances and I don't really buy much stuff at all. Maybe for someone else, shopping can be similar to an addiction where they see an ad and they know they shouldn't buy it but they can't resist. Women with a closet full of shoes come to mind. For those people I can see how this might be problematic but personally I largely ignore ads altogether. If I need a small thing I just go to the nearest store and buy the first best thing I find, if I'm making a more significant purchase I generally do some research and look at tests, user reviews etc. Sure there's some opportunity for manipulating me with fake/biased tests and reviews etc but I'm not really seeing how my spending info helps with that.
If you don't have time, you can find brief but less compelling argument here: https://www.privacyguides.org/en/basics/why-privacy-matters/
There's no advertising here, there's just aggressively trying to drain each person's wallet as much as possible and seeing how far you can get before they change behaviour.
One example: my friend and I both requested rides using the same app, standing next to each other to the same street in the same neighborhood 3-4 miles away. He owns a car and rarely uses car services, I do not and it's my primary transportation. The quoted cost of his ride was half mine. It was shocking.
And I'm sure there would be competitors simply not doing this where I could shop instead.
If Uber does this and you don't like it then don't use Uber. Regular taxis still exist and I'm sure they'd love to have your business back. Or you could get a car, low-end used EVs are quite affordable and fuel is almost literally free. They seem to hold good resale value too.