

depending on how you look
… and even more where you cross the border. If I want to go (like in “just walk there”) from Poland to Germany, I could use this bridge for example:
It’s really just an ordinary bridge across a river, no border patrol, no ID check, nothing. Just walk from one country into another.
Or if I want to cross the border from Germany to France, I could just use that publicly accessible hiking path:
(Seen from French side, the barrier where the people sit is the whole border crossing point.) And this bridge with a view brings you from France to Spain.
Except border check points you’ll find luxury housing on French side and commercial buildings (stores and some warehouses) on Spain side.
At no point in that imaginary journey (now that I think about it, this would make a great road trip with hiking parts) you need your ID card when you travel to another country.
Long story short: It’s really easy to cross borders in the EU.
Why would people in the right mind bind the right to vote to a document that allows you to operate a vehicle on public roads anyways?