The ones who will “always be there” can get their papers for permanent residence done and vote. If they don’t want to (or can’t since they don’t have the legal grounds to even stay there for longer), then they shouldn’t have a say on decisions that can permanently change things about the place.
There will always be the population of people who will be in short term housing or similar situations, but due to their circumstances the individual people will come and go. 5 years from now the makeup of the itinerant population may be almost entirely different, but the people in that population are in the same circumstances, especially if they don't have any political representation.
Who is going to speak for the people who aren't allowed to vote?
In my country, citizens without a permanent address (which is very few people, those who have no place of theirs mostly register at someone elses for easier administration) can still sign up and vote, so that leaves us with just the people who don’t have the permits to even stay here permanently.
I’m also not expecting to fly to country X, book an airbnb for 6 months or get a summer job, and then just somehow be entitled to vote there.
That is only possible with stable and legal housing. Not everyone is privileged to be in that situation, especially not with the housing market in many countries.
With your thinking you are creating a class of subhumans where you enjoy the benefits of their labour but you are not allowing them to vote. Like African Americans in the US not that long ago.
