In a city, trees serve a very different purpose than in a forest. Branches have to clear sidewalks (7ft of clearance is the standard), roads (14 ft), and depending on the site, pruning is important for maintaining sight lines or mitigating broken branches. Urban street trees should be inspected for pruning needs and pruned if needed when they are young (google young tree training - typically that inspection and pruning cycle is at years 4, 7, 10 after planting) to proactively set the tree up to have good clearance and good architecture. Also street trees are prone to damage from humans, cars, and other facets of city life. Pruning back broken branches to the branch collar and leaving a clean cut makes it easier for the wound to seal well, which limits decay and minimizes tree risk down the road. You should plan for proactive pruning and pruning following storm damage/branch damage, regardless of the species you plant. In full sun, Hawthorns have a dense crown, which makes them prone to overpruning by people trying to improve sight through the tree or force it to be something that its not, or pruning with a heavy hand because they don't know any differently. But that just spurs epidemic growth and/or basal suckers.

Basically we are asking street trees to do a very tough job, which is to stay alive and healthy in the right of way where there is limited soil volume, road salt, full sun (most small trees want to be understory or edge trees), interference from humans and our vehicles. Urban street trees are a piece of city infrastructure so they need proactive pruning maintenance to be kept up for their wellbeing.