I've always considered "cager" to be a combination of activity and attitude. I drive to work once a week, but like you, I don't rev my engine/lay on my horn/yell at/menace/hassle cyclists while I'm in my vehicle.
Motorist; sure. Driver; yeah. Cager; nope, don't think so.
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"I feel like my world was classier before I found cyclocross."
- Mandi M.