While I agree with the sentiment I'm not sure this is actually viable.

For example here in Poland the previous govt invested in huge amount of software for digital govt services. From company formation, social insurance/heathcare (things like electronic prescriptions and patient data) to tax submission at all levels.

All of this is implemented using publicly documented open standards so anyone can write a client for these services, or anyone can use official Web clients, but none of the code is open source.

This is in contrast to previous governments that tried to implement all of this using proprietary standards where the companies hired were paid billions to deliver a system and they ended up owning the data exchange protocol and a client they distributed in binary only form. And they also profited from commercial software that implemented their proprietary protocols.

That worked (for the company hired)for taxes and they made billions. But for other stuff like medical, when they had no way to sell their proprietary standards they wasted billions and years of time and delivered nothing. Then subsequent govt threw the entire project out and built it on open standards.

So based on this experience I think using well documented open data exchange standards is much more important than software itself being open source.

Who cares the server side software is open source if you still can't submit your taxes with your own python script?