→The maps providers
By default, the provider GRAMPS uses is OSM ( OpenStreetMap ). As a free project, we find it our duty to first and foremost support another free initiative.
OpenStreetMap depends on the community and the maps are very light depending on the country. Nevertheless, the community made an extraordinary job and the quality is improving rapidly. And you can help make it better! We can say OpenStreetMap is and will be the map GRAMPS uses per default.
Openlayers is free too and uses by default OSM map. A lot of private or non free maps depends on OpenLayers.