Because that never happens. TVs aren't affected by the price of milk. Your vacation in Germany costs the same whether you live in San Francisco or San Luis Obispo. Your iPhone costs the same. Etc. Etc.

If "everyone" and "everything" mean "the whole word population" and "all costs in the world", then yeah, nothing changes. But if it happens on a smaller region then oh, yeah. Lots of things change.

Thing is, it doesn't.

As an example cars are produced everywhere around the world but the same product costs roughly the same regardless of geography.

This way in rich countries people can afford domestically manufactured cars, while in poor countries they can't.

It's not that simple as the multipler is not even across all things and all jobs. Eating out or getting a take away is 2x or 3x the cost of the UK/US but your server & chef both make a decent wage without the need for tips. Electronics are about 1.2X the cost of the EU.

The starting salary of a supermarket worker is 2x that of the UK. But a software developer's salary is only a fraction more than in the UK.

The effect is that the range of inequality across the population is reduced. It's a social democracy, so in general the population like this arrangement.