That's an excellent attitude. You seem to be interested in researching this further, given the chorus of "deduction causes increased prices".

I'll try a different tactic for the explanation: What effect do you think the mortgage deduction has? Does it increase your disposable income?

Also, if a self-employed business traveler knows one can deduct the cost of hotel, flight, and meals (partially) spent during a business trip from income for calculating income tax, does that affect how much that traveller is willing to pay versus similar categories while not traveling for work?