Of course. It always depends on the value of a single purchase. It's much easier to hide the purchase of 2 small apartments than a big mansion in the suburbs.
For some small things it is not a problem to sell BTC and use fiat to pay for goods and services of lesser value. Theoretically, no one will ask me where I got my BTC with which I paid for a plane ticket or hotel accommodation, but the origin of the property is something that is a very serious matter in some countries. I think that in Sweden, for example, there is an online database where everyone can look at what someone else owns and compare it with their income, and in case they suspect some irregularities they can very easily report it.
In most EU countries they do it like this. When you buy property the notary has to report the value for tax purposes. The property and paid tax go into the database where they sometimes put the total value of your purchases against your paid income tax. If you paid very little = you had not much income and shouldn't be able to make that purchase.
Store purchases don't get reported this way. Nobody knows if you have a computer with a virtulal reality setup worth 10k USD in your room. Nobody knows if you have a swimming pool in the garden. These things don't get reported anywhere or compared against your income/taxes.
Water should be one of the basic human rights, and if it is on your property no one should ask you to pay taxes because you use it. And I know of cases in my country where people have to pay to use such water, but for now only if they use it in commercial agricultural production. A lot of things that were perfectly normal and free 20 years ago are no longer today, but it's just a result of the government's efforts to make people as dependent on the state as possible - and if you have your own water, produce your own food, your own electricity and maybe use Bitcoin - then you present a problem.
They are looking for money wherever they can, even if it means cheating people and stealing from them. I can give you some more ridiculous things the government came up with.
For instance, they are checking people's wells to find if they're not taking water from their wells and using it in the house. If you have such setup you are supposed to have a meter on your well water so that they can charge you for waste water.
They are also snooping around properties to see if people are not cutting trees without paying for them. Yes, you have to pay for each tree cut on your property and the cost depends on diameter of the trunk.
They are flying drones to check if people aren't building anything without permits. I'd agree if it was about the house, but they are comparing the pictures of your house with these made with drones to see if you did not add anything like a garage.
They are charging big properties with rain tax. If you have a big roof you have to pay for the rainwater. This is by far the most ridiculous tax.
Because of the above, I'll try my best to avoid whatever taxes I can and won't feel like a cheater or a thief. As long as the government will keep making up new ways to steal from me, I'll be doing the same.