It is with the hope that the penalties from getting caught will encourage people to comply with the limit of stay terms of their visa.

I've lived outside of the USA for most of my adult life and from the people I've interacted with, anecdotally, the threat that if they overstay their visa they'll be fined <insert large number here> per day and be denied a visa & entry in the future seems to motivate people to comply with the terms of their visa.