[veddox]

Principally the direct payments. Farmers in the EU get a certain amount of money for every hectare of land they farm. This accounts for 40% of all CAP payments, and disproportionately benefits large farms, as they not only get much more money but also benefit from economies of scale.

Adding to that, compulsory environmental regulations are quite lax, while voluntary environmental measures are often poorly recompensed, and are thus economically not viable.

See here for some further reading: https://doi.org/10.1002/pan3.10080 (There's lots more, but this should be a good starting point.)