At some point this stuff will have to get tested by making its way up the appeals stack in the US, and IMO there is only a minuscule chance that will result in Google, MS, and Meta getting slapped with anything more than a token fine (my bet is it won't even be that), let alone paying every person who ever wrote anything that was used in these datasets for copyright violations, which would basically be everyone.
Examples:
Japan: Article 30-4 of the Japanese Copyright Act. No special action on the part of companies is necessary for compliance. All models are legal so long as their output is legal.
The UK: s.29A of the Copyright, Designs and Patents Act 1988 (CDPA). Models must be trained by non-profit research institutes, and can then be used by anyone (including for profit entities); similar to the Stable Diffusion model.
The EU: Articles 3 & 4 of the Directive on Copyright in the Digital Single Market (CDSM). There are no restrictions on non-profit TDM, same as the UK. For-profit TDM is exempted from copyright so long as the data harvesting process respects an "opt-out" process, where specific contractual forms/disclosures of opting out of inclusion in the training data are respected.
Singapore: Articles 243 & 244 of the Copyright Act. No special action on the part of companies is necessary for compliance. All models are legal so long as their output is legal.
I think there's a strong argument for a Fair Use defense, given the size of the models versus the size of the training sets, as well as the gulf in intended use: an AI model doesn't compete with e.g. a book. Obviously we'll have to see if play out in court to find out.
In my opinion the most ethical outcome would be that they are on the hook for the cumulative cost of the copyright they violated. That way authors would come out ahead instead of having their rights trashed 'because it's too late anyway'.