It may be profitable to use CAPTCHA for AI training, but that's not only annoying, it's also unethical because one (like me) may be unwilling to engage in such activity. Also, CAPTCHAs involving houses, number plates or bikes are absolutely invading someone's privacy.
Owners of websites (e.g. shops) themselves have more options to show captchas only in critical moments: when performing heavy searches, registering, checking out, posting. Again, it doesn't have to be intrusive or disruptive. But I understand this way takes more professional approach and probably requires programming, which is not what _every_ store owner can probably afford.