I explained it as an example of companies not doing things to cancel out an increase in income across the board already. There is also the overall trend that increased income for large portions of the population means people buying more optional things, not the companies with essentials raising prices to match that increase.
This is like you demanding someone prove that Bigfoot doesn't exist. All I can give are examples where increased income being directly tied to prices/employee pay could have been proven to be a direct link, but wasn't. None of them are perfect because we don't have UBI yet.