Why would you? Some businesses live of high-volume low-value transactions (grocery stores, bookstores, etc.) I'm sure they care if you pay or not.
And yet they accept credit cards, debit cards, and personal checks (some even accept paypal!), all of which take more than 10 minutes to become irreversible and avoid fraud. Apparently most businesses are willing to accept a small amount of risk in the interest of increased transaction count and convenience. Fortunately bitcoin becomes irreversible far faster than the convenience payment systems that many of them are accepting currently.
Unfortunately "I wouldn't care personally" is not a solution and this is a tough barrier for in-person merchants to adopt Bitcoin.
Not for those with any intelligence or understanding of what risk they are already accepting by not accepting bitcoin.
I wouldn't even trust a guy showing me his mobile-wallet. It could be just a facade that does nothing behind the curtains.
Absolutely not, but as long as I had a well connected wallet of my own, if I saw a transaction on the network that included a reasonable fee and after a few seconds still hadn't seen any competing double-spend transaction, I'd trust it far more than any credit card, debit card, paypal, or personal check.