G-Suite is paid for with $, Gmail with your data/privacy
Might the difference be that Google doesn't dig into G-Suite data, but that it freely does so with regular Gmail and Google accounts?
'Smart' devices inherently gather private data and companies, including Google, monetize this. This fits right into messaging services like e-mail they give away for 'free'.
They can't do this with G-Suite because the (business) contract precludes it. If they were doing this (or going to) many companies would stop using their services - either because of concerns over data ex-filtration or because of regulatory constraints.