Because it is not the subject that will win them the next election.
And even if they care, some things are easier said than done. With politicians who care, you get things like GDPR, which goes in the right direction, but is a huge legal mess. And it is a mess because it can't be made simple.
Obviously, you have to take consumer interests into account, but you also have to take companies interest into account too, both big and small, otherwise they will just stop doing business, which is bad for the economy and will mean that consumers won't find what they want at a reasonable price. You have to think about the loopholes big companies will invariably find, and covering them will add complexity, but still make it so that small companies can comply without a full time team of lawyers assisting them.
For example, you say the consumer could return it for a full refund on a bad update, but to whom? Should the burden be put on the small retailer who sold it to you (and may be out of business)? There is already plenty of stuff the manufacturer must tell you, usually one a piece of paper no one reads, and the more you ask, the less people will read because there will be too much information. A "privacy score" may be a good idea, if well designed, it will share a place with the energy score, environment score, repairability score, safety signs, origin, etc... And how do you differentiate actual automated content recognition that consumers could want from spyware, formally, so that the first one is allowed but not the latter.
All that to say that it is not impossible, but even with politicians caring, it is complicated. European politicians care (because it can win them votes), the results are so complicated they are getting ridiculed by the rest of the world.