The devices just collected bread crumbs of data (for example, GPS points or 1 second samples of the vehicles speed). You need some horse power to process these

The devices just collected bread crumbs of data (for example, GPS points or 1 second samples of the vehicles speed). You need some horse power to process these into higher level objects like trips. In theory, it could be done on a cellphone, but a ton of extra data is needed inc volumetric models of an engine (to calculate fuel usage accurately). Doing it server side makes it possible to build this in an agile method vs going to every single make/model and getting this right the first time.