Automatic mixture control
Actually, we do have carburettors that compensate for altitude. Most bendix and TCM carbs and fuel injectors have an "automatic mixture control" option which consists of a small sealed bellows attached to a needle valve in the fuel jet. As ambient pressure decreases the bellows expands and the valve restricts the fuel flow.
Digital auto lean can also be fitted to some approved aircraft models under an faa stc. See here
https://www.aircraftspruce.com/catalog/appages/autolean10-06034.php
The main reason aircraft dont have these systems is related to increased cost and complexity and decreased reliability.