This is not the full picture, as you surely know.

Remote workers from rich countries do pay tax locally, in the form of VAT and sales taxes. And they typically spend far more than locals, on food to accommodation and everything in between, all while requiring nothing of the local welfare state. It's a direct wealth transfer of thousands per month, earned in one economy and spent in another. In purely economic terms, it's hard to see how this is anything but a good deal for the host country, in the large majority of cases. Hence digital nomad visas.

This is not to say that countries - and societies - don't have the right to allow or deny access to foreigners as they see fit.

Countries usually like tourism, don't they? But tourists are also living there and consuming services with no income tax. What's the difference?

One thing to note is that even if you're not paying income tax there, you're bringing tons of money into the country from outside. So that's worth something.

They don’t care too much as long as you don’t qualify for / consume social benefits like medical.

Immigration permission to work legally and tax compliance for the earnings are two completely different topics in probably all countries.

Even mostly law-abiding citizens with full work permission often dodge taxes in certain sectors of the economy - a common US example is restaurant workers underreporting cash tips on their tax returns. Plus, in addition to digital nomads, many freelancers (certainly not all) play as fast and loose with the tax rules even in their home countries as they think they can get away with. And much cross-border employment is disguised as independent contracting in ways that dodge employers’ tax burdens even when the employee has full work permission.

Conversely, there are already cases where even income earned illegally by visiting foreigners can legally be exempt from a country’s taxes. Example: Income earned in Canada by a US resident can qualify for Canada-US tax treaty’s exemption from Canadian taxation if the criteria listed in the treaty are met, regardless of whether the work was legal for immigration purposes. (Canada is actually one of the few countries from which foreign tourists can often legally work remotely for employers or clients abroad, but that depends on a lot of factors, and it can also be illegal like in most countries.)

The number of people affected (in principal that is, even fewer in practice) is likely so small that the political time involved would not be justified.

I think it is more for overstays. Years ago when I asked about my stayed days ( I was traveling a lot ) , border guard took passport and tried to count then gave up