https://www.apple.com/feedback/maps_ios.html
There are options to avoid toll roads in the map app. You'll need to goto settings > maps > Driving & Navigation then toggle on avoid tolls. I'm not sure if this will avoid HOV tolls or not (I think it should and if it doesn't it should be mentioned in feedback). Although just driving by them will recalculate.
BTW for your trip just leave an hour early take i95 north to VA-267 and you'll start seeing signs for dulles international. From there its going to be a left exit right into the airport. I think parking is free under 1 hour so if you make good time just meet your friend at the gate. If they are really good and patient friend leave on time and have them wait at the curb so you can just pick them up. I was browsing this forum sitting on my suitcase at Baltimore Washing International 3 hours ago for friend to pick me up for about an hour (stuck in traffic) but I would happily wait then rent a car, taxi, uber etc etc...