Re: So net loss to the taxpayer
Actually, it's not any kind of loss to the taxpayer (at least not directly). The ICO is not funded from taxation (to avoid any suggestion of conflict of interest if it takes action against a government entity). Nor is it funded by fines (to avoid any suggestion of vested interest). It's funded from the registration fees, which, although not proportional, are scaled in accordance with the size of the registrant organisation.
Given this position, going after large companies has clearly nothing to do with revenue for the ICO, but it may be good for raising its profile, and that could well be necessary if the ICO wants to remain recognised by the EU. That in turn could at least unofficially affect whether or not the UK gets its adequacy decision swiftly (or indeed at all).