Retailers have been conditioned to think that fraud is simply an unavoidable cost of doing business. And, year in and year out, they factor into their budgets whatever percentage of sales they are comfortable writing off due to not only fraud but also fraud prevention, which has traditionally been strongly risk-averse and often blocks good sales, as well as fraudulent ones.
Merchants have essentially accepted the fact that they will just keep losing money to fraudsters, no matter how they try to beat them back.