We need to stop building a world without trust. Always checking, ensuring, surveilling (,mining on a blockchain), this is anti-human and will only lead to unhappiness, burnout, depression. It's no way to live unless we want to be like the Borg eventually.
That's what you get with larger organizations. But these large organization is what allows for the specialization and economies of scale that make up modern civilization. For example, if you go to some big box store and forget to make you pay for something, I don't know many people who will point out the mistake and pay their due. The same people will probably be more inclined to do so if the shop in question is a sm…
The country may not trust their citizens when it comes to paying taxes, but it's not an absolute lack of trust. They set up regulations outlining rules and punishments, back them with various enforcement mechanisms, and... they trust it's enough for vast majority of the citizens.
They trust most people will be nudged towards paying the right amount of taxes - that's why they don't generally surveil every single transaction you're making. It's hard for a regular person to get on the IRS radar in a way other than interacting with government services in a weird way somehow. When they notice something suspicious, they will follow up, but the process set in the aforementioned laws is again very much trust-based, giving the suspect the ability to explain themselves at various stages, and not digging through one's entire life until late in the process. It's based on a reasonable assumption that most of the issues a country's IRS would flag are honest mistakes.
Same with every other process in most (all?) societies. There are directions, nudges, deterrents. Not total surveillance. But the newest trends in technology businesses seem to desperately want to move us towards the latter.