"such a high proportion of companies are allowing employees to share confidential company data on personal devices, using outdated apps as well as knowingly operating in breach of GDPR rules."
For companies that weren't prepared (most of them?) it's a matter of doing ANYTHING necessary to continue business operations immediately, or else having to close up shop entirely and everyone finding new jobs. Given that, risking a GDPR fine doesn't seem a bad choice...
Of course they've put themselves in this position by not having working DR plans, and not having enough IT staff to do things properly, etc. But right now, companies everywhere are breaking all kinds of rules to varying degrees, and just hoping their luck holds out and the fallout won't be completely devestating. Look no further than COURTS using Zoom...