"So, if you are plugged in somewhere (home or work) and the network needs you power it can drain your car battery and then when you go to head off for work in the morning or home from work your car is flat?"
In theory that is possible, in practice any power retailer that tried that would lose customers in a hell of a hurry.
V2X works with continually variable tariffs and consumer controlled software. As a simple example battery SOC more than 80% will sell power for 30c kWh or buy for 10c kWh. Battery SOC <80%, sell 50c, buy 20c, SOC <60% sell 90c, buy 30c, SOC <50% sell $1.50 buy 40c, SOC <40% no sell, buy 50c. I expect there would also be a provision for the power utility to borrow power at say 10c kWh on the condition that it was returned before a certain time. Each time a "transaction" occurred it would of course be documented by the car and power utility to ensure transparency.
"I have heard people complaining of power being stolen from their home batteries."
Wally, maybe you could back that up with some evidence, you have a habit of engaging keyboard before putting brain into gear. Should I remind you of your Lithium battery RTE post on another thread, it was a bit inaccurate too wasn't it.
