Same for Austria, which interestingly was considered a "test-market" for international carriers, thus we always had the cheaper contracts and some novel business models quite some time before the rest of the EU (unfortunately not network generations or coverage in general).

The answer is money. Tethering was usually not allowed but you could buy in. You get phones for free, but only if you pay 40€+ a month for the next 2 years for something you actually don't need. E.g. some unlimited services (streaming) while your general data is capped.

I haven't been in the market for such contracts for quite a few years, this has changed a lot in recent times due to "contract-less" cheap providers gobbling up the marketshare. And these packages always disappeared over time and became standard. I don't think tethering is not allowed anywhere anymore.