I think the whole payroll, invoicing and accounts side of things is all running on third-party software, so the people who develop Google's own publicly-facing code don't have anything to do with it.
The article linked in the first article has Google claiming it has gender pay parity early on in the dispute versus the government saying this is a bad situation based on the sample of data the government received. The original article then has Google saying it cannot produce the data behind this gender pay equity claim. It seems logical to anyone who is not a lawyer that the plaintiff, Google, cannot have it both ways in the very same case, in fact it seems positively ludicrous.
Sure. And they have enough money to hire a firm that specializes in e-discovery and/or assign clever employees who have experience doing good, challenging work to put together data sets from disparate sources.