My point in mentioning, rent utilities, a car payment, insurance, et. al: while "proportional salaries "might be a myth, the cost of living where, and in the manner in which you are accustomed, isn’t. You might be surprised how many people, in the excitement of receiving a job offer, don’t consider this when negotiating a salary.
And of course you are correct. As an employer I wouldn’t care about the size of your debt, how much of your salary you spend, or if you’re supporting your grandma, or if you have to eat ramen noodles four nights a week to afford your apartment, all I care about is how much you cost me.
I would however be mildly curious to know if your potential employer asks for access to your credit information. It seems to be a trend in the last few years to collate a candidates credit rating (more precisely repayment habits) with reliability in the work place.