Well, that's a good enough reason to me to chuck the system and go to a flat tax or sales tax. Or, better yet, just take the tax burden then divide it by the population and send everyone a bill:)
BTW, if you consider this money out of "your pocket" then you are getting hit from all sorts of areas. Whenever there is a deduction you can't take advantage of. If I agree with your premise then so am I. And I don't agree with your premise since when someone takes advantage of this deduction YOUR taxes don't increase because of that. I don't see where someone says "isthisnickcool just purchased another huge box on wheels! Call dogbyte12 and tell him/her their tax bill is going up".
But I do get your point and I'll agree with it long enough to take the time to thank you for my new wheels. Just kidding:)
How would that change anything? Tax all businesses on their total gross, not on the profit made? So a flat tax on a business making 1 or 2 percent over costs would be taxed at a rate of 30 or so percent of their gross resulting in a loss of 28 percent? Only the rich and stupid could operate a business that way (and they wouldn't be both for long).
A flat tax would only apply to profits after costs of doing business. Vehicles, equipment, supplies, etc. are a part of the cost of doing business. A flat tax would change nothing, just make it a tiny bit easier to calculate the final total due.
Sending everyone a bill for their yearly share and making them pay it might be a nice step toward fiscal responsibility though.