The paradigm of 18th century economic theories, which I doubt that you sincerely subscribe to excepting this one matter, is no longer relevant. When the power wielded over, and the access afforded to an individual by a private corporation is so great that when denied access that person has no meaningful alternative and is meaningfully and irreparably harmed, that does become a matter of public concern. Whether or not users were informed when signing up that google would come to hold the keys over almost the entirety of their identity as it exists on the internet, and that their identity on the internet would come to represent a huge fraction if not the majority of their identity in the world, that is the circumstance we find ourselves in. Our identity on the internet is for most, an essential and non-negotiable element of the infrastructure of the modern world. A person who loses access to that identity may very well be losing access to their only means of employment and their only means of communications with certain friends and family members, and documents that are critical to their freedom and identity in the physical world (scans of passports, birth certificates, vaccination cards.)
The fact is that these corporations are not innocently providing simple little services that users might occasion to use for a bit of time and then freely put down; they provide services that grant them at times more power than nation states over the lives of individuals who are completely powerless to respond. Given that they wield power over a service which is not optional for most of their "clients", whether or not they meant to (they meant to), they are providing a public good. And if they are unwilling to do so in a way that aligns with the values of the citizens of ostensibly democratic nations, then the citizens of those nations should vote to either compel them to offer their services in alignment with the public good or have their property and right to conduct business in that nation seized.
And whether or not many are aware of it, this would not represent a sea-change in policy for any Western government that I know of. This would simply be the very late, but reasonable extension of more than a century of well-established legal precedent that already exists. For example, in the United States, we call corporations that are regulated in such a manner "Public Utilities", in Germany they are called "Öffentliches Versorgungsunternehmen" and in France they are called "Entreprises de Services Publics" and in Spanish they are called "Empresas de Servicios Públicos"
