I'm just confused. Why can't people have second tech jobs? Cashiers can have second jobs working in a different store. Factory workers can work in other factor

I'm just confused. Why can't people have second tech jobs? Cashiers can have second jobs working in a different store. Factory workers can work in other factories (it's hard on your body but overall okay). No one would similarly complain if an Google software engineer was also 'forced' to make ends meet by working in an Apple retail store. Yes, it's hard on your body and mind to work more than 1 job, but if you need the money then what choice do you have?