They pre-crush grain because most people don't want the expense of a mill and are willing to pay a higher price for crushed grain vs uncrushed grain. The footprint of a grain mill is also significantly less than if you were trying to sell numerous starters.
Finally, there is something clearly wrong here if you find making a yeast starter too difficult or time consuming that you need to pay someone else to do it. It takes at most 20 minutes, and that includes cooling and cleanup time.
My starters usually take 3 days. A lot can change in 3 days.
KNow what'd be even better than if they made a starter for my lazy ass? If I could just go there and use their equipment and they clean up the mess.