Well, college level Calculus is not simple, and is required for most BS and STEM degrees.
Amen! I, too, worked full time pulling orders at a grocery warehouse in hot Alabama (no A/C in the warehouse) while taking a few courses per quarter getting a computer science degree (which included two courses of "college level Calculus" LOL). It didn't kill me. It allowed me to have good work ethic, appreciate the software jobs I had (easy breezy compared to the warehouse work), make nice money, and finish college with little debt.
Calculus was actually fun and easy for me. The math classes beyond that is where it got to be a challenge.