You usually have to make a large number of simplifications to create a Physics model too. The question is how those simplifications change the accuracy of the model.
"Essentially, all models are wrong, but some are useful"
-George E.P. Box
We can generalize to more than just physics and economics... As the quote says, ALL models are wrong (no matter what field). If you have a model that is "right" then it isn't a model, is it?
"Essentially, all models are wrong, but some are useful" -George E.P. Box