It's why we ended up with a sluggish health care market unresponsive to individual desires -- leading to the insistence that we need a government-managed alternative like Obamacare.
The code is incomprehensible. You can get a deduction for feeding feral cats but not for having a watchdog, for clarinet lessons if your orthodontist thinks it'll cure your overbite but not for piano lessons a psychotherapist prescribes for relaxation. It seems so arbitrary.
In the marketplace, individuals shop around for the most efficient, low-cost way of getting services they really want. Every time tax rules nudge us in a chosen direction, they preempt the market's signals.
Government gets moralistic about it, too, placing "sin taxes" on items like cigarettes and fat, plus luxury items like yachts that some find decadent. It's gone on for centuries. American colonists seem libertarian by today's standards, but they put extra taxes on snuff and "conspicuous displays of clothing."
That's one thing the Founders did that we shouldn't copy -- but their otherwise rebellious attitude toward taxation is one that we should emulate. America suffers when government turns taxes into a manipulative maze.