Your assumption about agents basing list prices on commissions isn't entirely accurate. First of all, agents tend to price properties to sell quickly so their chances of getting a commission are almost guaranteed. This doesn't always mean the home sells for the highest possible price [1]. In order to determine the list price, agents will runs comps to ensure their listing is competitive against the other listings in the area. Ultimately, the buyer wants the best bang for their buck.

If there's high demand and low inventory, agents will naturally up the price. Supply and demand.

[1]: https://www.youtube.com/watch?v=17jO_w6f8Ck