Of course it's a social construct, just like everything else that matters is. If you don't want your live to be determined by social constructs, you would have to live alone in the woods.
Failure to pay someone money they are owed resulting in jail time only sounds good when you imagine employers being carted off for not paying employees what they're owed.
It's not so fun when you consider a mother of 2 carted off for missing a car payment.
Crime is a social construct = wage theft is a social construct, and according to the law of internet arguments something being a social construct means it doesn't matter and/or it's dumb to complain about it, so don't worry, it's all fine.
Unpopular opinion: I find this comparison a bit off. Compare your theft from the till to your boss taking $100 from your pocket and it seems more even.
Setting aside morals and ethics for a moment, intent (and malice) is a key component of crimes. Unfortunately it's easier to show in some cases than others. It's also worth noting that the at-will contract goes both ways in this case. Unfortunately there is an insurmountable power imbalance in this situation.
I was about to say I'm glad I was never in this situation, but I just remembered a time where I switched from an employee to a contractor and stopped getting paid.
Just because the rich are protected from their white collar crime doesn't mean the concept of crime as a whole is a social construct.
Crime exists, crime is crime. Your boss short changing you money wouldn't get the same reaction as lifting money from the till but you'd still have legal recourse to either get the money from them or take legal action to sue them.
Double standards under the law doesn't equal "crime is an invented concept."