That seems illegal in some places if true. The premise is that it proves we are not robots, and that's all.

By tracking you, they can remember that you are not a robot. As much as I dislike tracking, I don’t think having the captcha be always hard would be all that great either.

Ideally I’d like to see fewer captchas. But there’s no good alternative to it really. I mean, requiring phone verification instead is an alternative. But I don’t necessarily want to hand out my phone number to each and every site on the net that I interact with either.

Its absolutely not true that there is no alternative to tracking for captcha "hardness".

https://privacypass.github.io/

You can prove trust once and get several tokens to spend later. There are various people looking at this like Cloudflare and Google.

Wow didn't know that. Do you have a source?

How do they decide which captcha is harder ?

The parent used wrong phrasing but it's real. The captchas don't become harder to solve but longer. If Google detects you're blocking trackers (or possibly cookies) it will throw at you an huge number of captchas until you give up. Imagine having to click like 12 panels of street lights, cars, bicycles, trucks, buses, etc. sometimes multiple times. This is getting out of control, really. I miss so much the Web 1.0 from 1999.

What I do on captchas is to hit the skip button until it would prompt you to verify. You can try if this could help. Captchas should be tone down to something bareable. I even got to a point that I'll drop the site because of this.

the worst part is when cloudflare puts you on their shitlist and you have to fill out these dumb captchas for 6 minutes before you can even access just about half of the sites on the internet

It's really sad the situation we have come to.

I think that only two things can defeat this madness

1. Legislation

2. Breaking captcha to the point it's not effective anymore

I use Firefox with all the privacy stuff turned on. I have to do multiple, difficult recaptchas all day. I've even missed out on Yosemite campsite reservations because of the delay from all the captchas presented to me when trying to book :(