There was one more group of people who were even more suitable to pilot Carmine mechs aside from infantry soldiers.
There was nothing particularly wrong about converting infantry into Carmine mech pilots. Even if they never came into prominence due to the idolization of mech pilots, it was incredibly cheap to train and employ these troops.
As long as there was no demand for elite commandos or whatever, the cost to raise and employ an entire infantry troop from scratch for several decades could never exceed the cost of purchasing a single mech!
However, most groups knew it was useless to field millions of infantry soldiers on the battlefield.
A few mech companies would tear them to shreds, mostly at a distance but also up close when it suited them. The combat power of a single mech was simply too much, and their effectiveness rose when they fought alongside other complementary mechs.