Mostly just usability.

Also somebody to call (or sue) when it doesn't work right.

Many open-source programs have great usability. It’s just that a lot of people define “usability” as “works as closely to Microsoft equivalent as possible”, which is not really fair.

Basically all Microsoft software is bad. It’s obtuse, slow, unintuitive garbage. But people get very used to it, and are fantastic at navigating around and getting their job done. I should hope so, they’ve had decades.

Governments are free to pay consultants to fix it. It's Open Source after all.

If even a tenth of all government licence fees went to improve open source alternatives, they would surpass Microsoft within a year. And every human on earth would benefit.

Instead we're being extorted by Microsoft for buggy software

Good luck with MS support when things go wrong. Your ticket will bounce between 7 different engineering services which will try their basic debug script before tossing you to another department, all after calling you at 4am.

Also, MS doesn't care anymore since they have the monopoly. Things go wrong? Tough shit you won't migrate somewhere else anyway, and will continue to spend millions for licences.