Interesting. I have never worked anywhere where you can't take the vacation as cash when you leave. Isn't it illegal to keep it as it is earned income? I would be surprised if an employer can keep the cash as the employee already earned it. I would look into that.
I don't think one way is better than another. That has never been my position. My position is solely that the cost analysis is more than just gas and tolls. There are other costs involved including vacation days, wear and tear on the auto, etc. Still might decide to drive or fly or whatever but the math is a bit more complicated than just gas, tolls and hotel.
Have a safe drive