I'm not quite sure why people think a world running on bitcoin wouldn't have any taxes - The men with the guns don't care how you pay them: paper, silver, gold, bitcoin, they'll take anything if it means they don't have to work productive jobs.
Discussion
Because taxes only exist to control inflation under our current money system.
In the 1970s we stopped using money and started using debt tokens.
Before that, taxes were needed for spending.
But now almost all public spending is new money, while taxes are destroyed, taken away from circulation to control inflation.
Bitcoin 100% solves the issue and does not require taxation to control inflation
I'm very sorry but that is mostly the MMT argument. It's true that in 1971, Nixon essentially ended Bretton Woods and made the dollar no longer redeemable in specie but there have been taxes before that, even when the gold standards of the world were fairly rigid, there have always been taxes as long as there have been wars or standing armies.
There is a graphic here:
https://usafacts.org/government-spending/
that details how much revenue the US government has made and how much it has spent. The deficit (i.e. the percentage covered by debt rather than taxes) is about a third which is mind-boggling but even in the current system, spending is mostly tax-financed.
Your argument of taxation being price level control that your friendly government uses to help you originated in a school of thought called Modern Monetary Theory which is essentially Keynesianism on steroids but not based in reality, in fact taxes very much are revenue.
But even if everything I said was false, imagine what the theoretical switch to bitcoin would do to government budgets:
They can no longer create new money and thereby inflate away your purchasing power while increasing theirs so how are they gonna finance themselves?
A bitcoin-based monetary system would be the best there had ever been and I would do a lot of things to bring that about but as long as there are governments, there will be taxes.
The Mises Institute (misesmedia on YouTube) have a lot of resources on Austrian economics, monetary theory and all kinds of related things if you're interested, here's one for example:
https://youtu.be/bKGW1lN1u-M?si=AVrji4q9xpxnqcsS
So again, I'm not trying to be mean or anything but fixing the money, while absolutely necessary, is only step 1.
I’m think it’s mostly because:
1) if a government pushes too hard with taxes, ppl will flee to a friendlier jurisdiction (the sovereign individual book thesis is coming true on this)
2) if your wealth is stored in houses, physical businesses, or bank account, it’s easy for the government to freeze them and make your flee harder. If your wealth is in btc its way easier to flee with your wealth
These are 2 ideas that come to mind on how it will be harder and harder for governments to impose crazy taxes
I grant you that BTC is harder to outright take/confiscate/steal as a bank account or a bar of gold but most people are employed in some way by companies who operate on the government's turf - and the government expect their cut, so they'd pressure those companies to reveal how many sats they give you just like they do with dollars and pounds right now, and the people coming to collect shoot to kill if necessary.
And about fleeing, I really wish it would be the case that people would actually "vote with their feet" in massive numbers but most people are bound by family, culture, or language to the area they live in so unless circumstances become unbearable (see perhaps California) or countries become way smaller (the South tried that, see how that treated them), the local government will always have massive power over those unwilling to cut and run, and enhanced wealth preservation with BTC, while solving a great deal of problems in many areas, would likely do very little to rectify that.
Please don't get me wrong, I'm arguing these points out of something like academic interest and to warn people that their well-laid plans might well be thwarted by the government but always in the hope that people come up with ways to affect lasting, unstoppable, positive change.