Cloudflare does not do this - I've made that point several times. The website operator either has the security setting cranked to a paranoid level (which is not the default, btw), or they are experiencing an attack. Those are the only two scenarios where Cloudflare is going to inject a challenge as frequently as you assert.
Normally Cloudflare will only challenge after unusual behavior has been detected, such as inhuman numbers of page requests within a short duration, or the URL/forms are being manipulated, etc. The default settings are fairly unobtrusive in my experience.
If you are also complaining about generic captchas on forms and what-not, that's a different thing entirely. Those exists as anti-bot measures, naturally, but also as anti-human measures. We simply do not want a pissed customer to send us 900 contact-us form requests one drunken evening...
