And not just that, but only extremely rich people have truly personal assistants, and if they can afford them then they probably don't need this apparently mass-marketed service. Most "personal assistants" are hired by a company that the said "rich person" is involved with, making it a company expense. And why would a company with the resources to hire a personal assistant (and likely other flexible personnel) go to some $100/hr service when they have their own employees to service their general needs and who can be responsible for tracking down and hiring the specialists who actually do those tasks.
I mean, seriously. You could hire a full-time minion to go out and find and pay specialist deliverers, caterers, etc. for a similar or smaller cost than it takes to hire someone unknown and unreliable to do it ad hoc for a quarter of that time, given that 40hr/month estimate.