I don't see how buying gift cards for cash in person is less secure than buying something online for bitcoin. Cash would seem the least identifying and/or trackable way of purchasing gift cards.
One can easily use VPN services and Tor to anonymize IP address. And one can easily anonymize Bitcoins using various mixing services via Tor. But in buying gift cards with cash, there is in-store video. There's also cellphone tracking, for those who are careless.