The difference is that government regulators (in the US at least, but presumably in many other countries soon) have stated that they consider bitcoin exchanges

The difference is that government regulators (in the US at least, but presumably in many other countries soon) have stated that they consider bitcoin exchanges to be money transmitters and therefore regulate them in ways that prevent money laundering (http://blogs.reuters.com/financial-regulatory-forum/2014/01/06/u-s-treasury-cautions-bitcoin-businesses-on-compliance-duties-advocate-cites-chilling-effect/ http://blogs.reuters.com/financial-regulatory-forum/2014/01/...). I suspect most lawyers/regulators would consider changing bitcoin into gift cards is legally like transmitting to cash. Cars are regulated also, for instance to post a license plate that can be used to identify the owner's name and address, in part because they can be used in crimes. This isn't _just_ an issue of if the seller is being ethical; it's an issue of whether they're following the law.