This is great idea, but for a real time game like ToS it should be a tiny popup in the corner of the screen - something like a small non-disruptive Popolion pop-up which provides a captcha at random times with a reasonable timer on it (so you don’t have to do it in the middle of a boss/world boss).
The reward for beating the captcha should be a minor stackable buff (up to a certain point, or a useful reward - NO TALT PLEASE - maybe a golden anvil or something) that lasts for whatever duration IMC wants, hopefully permanent until log-off, and failing (upon multiple tries?) or letting the timer run out you get said debuff which quickly reduces all sources of income.
The more you fail / let the timer run out, the more frequent the captcha becomes (like 1 every 5-10 seconds), so people who afk won’t be effected too much - say they have to input 2-3 correct captchas to completely erase the debuff for increased security so bots would quickly become obsolete as they have difficulty dealing with a single captcha already. And manning bots would be way more annoying having to deal with x amount of captchas with, however, many bots you’re using - though people who bot with 1 character, and are constantly surveying it, would basically be lazy real people, who’re just trying to grind past a certain point - but everybody knows that the real threat are those who bot with an army.