Spellforce 3 (and likely others from the series) has carts that move resources between outposts. These can be attacked. It's not exactly what you're after, but

Spellforce 3 (and likely others from the series) has carts that move resources between outposts. These can be attacked. It's not exactly what you're after, but more than most other RTS games where resources can be deposited anywhere and picked up anywhere.