Most Paratransit and I believe even MetroAcess is also 5 minutes from Vehicle arrival. The 15 minutes is a window before and after the requested time. So if your time is 9:00, you have to be ready from 8:45 to 9:15. If the vehicle arrives at anytime, you have 5 minutes or it's a no-show. I'd be shocked if any Paratransit vehicle that is ridesharing can wait 15 minutes for every passenger because the whole route would break apart. But I often find people get confused about windows. I work in Software and Transportation.

Edit: Yep, just looked it up. Pretty standard.

Pick Windows > Pick-Up Windows When trips are scheduled, MetroAccess assigns a pick- up window, which is a time period during which the customer is scheduled to be picked up for their trip. These windows are 30-minutes long, and allow for traffic and other delays.

> Customers should be ready at the beginning of the pick-up window. For example, if a customer schedules a trip for 8:00 a.m., the pick-up window is from 7:45 a.m. to 8:15 a.m. The customer should be ready for pick-up at 7:45 a.m. Customers typically receive a courtesy phone call upon vehicle arrival and should be prepared to display a valid MetroAccess ID card and pay the exact fare before boarding the vehicle (if the fare has not been prepaid via EZ-Pay).

Customer No-Show and Late > Cancellation Policy No-Shows Upon arrival within the pick-up window, drivers are required to wait five minutes for customers. Within that five minutes, customers must present themselves for boarding. A “no-show” occurs when a customer does not present themselves for boarding within five minutes of the vehicle’s arrival (within the 30-minute pick-up window).

Customer Guide to MetroAccess - WMATA (Page 12) https://www.wmata.com/service/accessibility/metro-access/upload/MetroAccess-Customer-Guide-2021.pdf

Although they may wait longer if they BOTH have contact with the rider and if they are still on-site and it doesn't make them late to their next stop. If they had to wait 15 minutes it would ruin ontime performance and wait times, which is the metric they focus on and the article says is lacking. They also might have been lenient during the Pandemic, which is what would happen if you have a surplus of drivers and scarce amount of trips.