The difference here is that the second job you have is likely going to be just as terrible as your first, where the improvement comes not from having a better job but simply having access to more hours and therefore more hourly pay.

Searching for a job that is _mechanically better_ (think office job versus min-wage retail) is significantly more challenging than finding a min-wage job. For example, most salaried or otherwise higher paying jobs require multiple rounds of interviews while many min-wage jobs will hire you on the spot to fill a staff position.