EXAMPLES OF OPEN SOURCE
Zoom has become a trend even though the open source alternative Jitsi works just as well. Not only is Jitsi free, but you can set up your own server if you don't want to use someone else's. This means that the government could have its own servers for video meetings in a security room only accessible to authorised people, such as electricians, and other workers who may be needed, instead of needing Zoom or Skype for Business.
Another example is Linux. Windows could easily be replaced with Linux variants that are similar to Windows in how you find programs, navigate and do things. Most often, public sector computing is used only for documentation and web browsers - two things that are included in Linux.
For the office package, there are also good alternatives. One example is LibreOffice, which does the same thing as Microsoft Office, but at no cost.
WHY ISN'T OPEN SOURCE SOFTWARE USED?
The main reasons why so few people choose open source software is because many organisations and individuals are used to various pay-per-use programs, and because pay-per-use programs are the only thing we become aware of through advertising.
Another reason is that companies like Microsoft have a lot of lobbying power. Brazil's public sector was supposed to use open source to avoid the costs of proprietary Microsoft options - this was not the case, Microsoft fought back. (Kingstone, 2005)