Gmail is probably squeezed in on the servers running GSuite (the business version of Gmail). And I imagine it's very profitable from small/mid even large businesses.

Same with maps.
There will be companies that have tracking and planning software built ontop of maps, and for these uses it requires API keys.

General users using it for free will provide great information and data (eg, detecting/tracking traffic jams), but their usage probably "fits" around the paid usage