If Holland is anything like Denmark the cost of employee phones can be budgeted as an operational cost, which means it's basically free. I doubt that is their reasoning. It's far more likely this is a part of the massive anti-US tech dependency wave which is rolling over Europe. Digital sovereignty is a hot topic these days.

As far as what people want... it depends... A lot of people have two phones anyway, since they don't want to pay the additional taxation for using a company phone privately. Also because it's easier to turn it off when you're not working. In education I would imagine a lot of teachers/professors would prefer to not give their private numbers to students.