If a shopkeeper buys a box of toothpaste to sell, he does not pay sales tax on the purchase of the toothpaste. Why? Because s/he's purchased the toothpaste with the intent to sell it for a profit, and on those profits s/he will pay tax. If the shopkeeper, for some reason, sells it at a loss, s/he pays no tax.
My answer to the assertion that an FTT is analogous to a consumer sales tax (something people seem to be terribly confused about):
If a consumer buys a tube of toothpaste from the shopkeeper s/he may pay a sales tax because s/he has no intent to sell it for a profit, but to use it.
When someone buys a stock, s/he does so with the intent to sell it (there is no other use for a share of a company, really). When s/he does so, and makes a profit, s/he pays a tax on that profit. Just like the shopkeeper.
The financial transaction tax would tax losses as well as profits, and this would impose a heavy burden on the financial system...and on every single retirement plan out there.
The question, then, is not why financial transaction taxes shouldn't be treated like any other transaction, because they already are. The question is, why should they be treated more harshly than any other kind of transaction, because that's what a financial transaction tax would do.
It's a snake-oil remedy. I pray we don't fall for it.