I have found that the normal map applications I've used only highlight the large networks like Electrify America, EVGo, Chargepoint, etc. if they even have the functionality to show chargers in the first place. For example, google maps doesn't show many of the chargers I frequently use, like the Kwik Trip charging network. I've even tried to add them to the map but the changes have been rejected every time.

The benefit of a standalone app like plugshare is that it's crowd-sourced and generally more up-to-date. People can add new stations as they come online regardless of network and leave reviews with helpful info like "charger #4 is broken" or "the charging cables are short, you might need to back in". For the larger networks, active capacity is also shared in the same way that google maps shows (e.g. 6/10 stations in use). It also lets me do route planning based on my expected range and save it for later or or open the route in my gps.

To me, all that is way more useful than what I get out of the built-in google maps in my car, where the charger selection is limited and the gps will arbitrarily select chargers on my route if it's too long without giving me much choice in the matter.