Constituent - “ any of the voters who elect a person to represent them.”
H1B are not US citizens, and politicians considering them their “constituents” are misrepresenting their true constituents interests.
For certain policy aspects, such as national security and defense, it absolutely makes sense to actively exclude and ignore the concerns of non-citizens. They are really not 'true constituents'. But for most other things, the person who's considered a constituent is a law-abiding, tax-paying person, not a persona non-grata (that would be the illegal immigrants aka 'undocumented immigrants' whose cause is taken up with gusto by both political parties); it is absolutely the responsibility of the elected representative to pay attention to his concerns.
Same with prisoners being not allowed to vote.
How can you have a representative democracy where only some of the people are represented, and laws are made that determine who goes to prison for political reasons (such as using cannabis for example)?
The Brexit vote in the UK is a great example of this injustice. It is often cited as 52% voted for Brexit.
But the people most affected are the residents from EU countries other than the UK. They are of all ages, and have been told, some their entire lives, that they have the same effective status as UK citizens in virtually every way.
Unlike most systems, the EU-UK system did not require visas, documentation, or place restrictions on people. They were allowed to do virtually everything any citizen can do, and advised in effect that converting to actual UK citizenship is a pointless formality, which even the UK state would not encourage. In effect they were "virtual citizens" already. Many are part of multi-generation families in the UK by now.
And then a decision which affects them most of all is passed without their input.
There are millions of them. About 5.5% of the entire UK population. If they had been asked, there is no doubt from the numbers that the result would have gone decisively the other way.
A prime example of "taxation without representation" and all the other things like that.
On top of that, another group very much affected: UK citizens living in the EU. Some of those retired are now in difficult circumstances, as they lose rights where they are settled, and can't really come back to the UK either. Those living there long-term were not allowed to vote on the issue even though it severely affects them; that number is about 1% of the UK population.
A prime example of "screwed without representation".
This is actually acutely important to both the history of the United States of America and to a grasp of how a representative democracy (if the US is to remain one) works
So, let's go back to the mid-18th century. America is a colony. The colonists are unhappy because they feel unrepresented, but in Westminster, London, the Members of Parliament are content that indeed those colonists are represented - by them - even though the colonists don't get a vote. This concept is named "virtual representation" and we'll return to it. The colonists oppose it, "No taxation without representation" they cry.
It is worth taking a moment here to consider that those Members were not elected by the majority of the people in the districts they were elected to. Only wealthy men in England could vote at that time, a tiny fraction of the population who'd be affected by the Parliament's decisions. This is also prior to Great Reform, so the districts represented do not closely resemble one another in population (though next century things would get much worse before they got better)
So, the Americans revolt, and having won their independence they set up for themselves a new system of government. In many ways this system is reminiscent of the one they've just got rid of, except that (no surprises) the rich old white men who didn't like the old system are instead placed in charge of the new one. In particular, the United States of America does not in fact enfranchise all its citizens, it actually only gives the vote to wealthy men, almost exactly the same as England had done. Still, they now feel represented (and indeed have become important political figures in their new country) and so for them it seems mission accomplished.
The US Congress offers exactly the same weak rationale as the English parliament, virtual representation. Sure, women, the poor, slaves, children and so on are not allowed to vote but we promise your Congress people are representing you anyway.
And so that's the status quo. Either you aren't really a representative democracy, with your millions who are disenfranchised for various reasons†, or you accept that representation is necessarily distinct from enfranchisement - the right to vote.
† In both England and the US the franchise was greatly expanded, to include more men, and eventually women, but although such expansions are almost invariably described as "universal" by their proponents in both countries many people can't vote, and neither is close to even achieving the more reasonable standard of allowing everybody who can meaningfully express an opinion (which would rule out newborns for example) the vote. Not least both prevent people from voting if they are in prison, as if somehow prison reform wouldn't be a very significant issue those people might now have more insight into than other voters...
The US is EXTREMELY happy to collect taxes from people around the world and to call them resident aliens for tax purposes if they stay in the country for more than half a year or a given combination of days in the preceding 4-5 years.
Of course, being a US citizen it's a little bit different, you have to declare and sometimes pay the taxes in different countries.
How does not having citizenship make it harder to pay taxes?
So many people believe non-citizens don't pay taxes. So many people believe non-citizens are undocumented, not allowed to work legally, etc.
The vast majority of non-citizens who work pay taxes the same as citizens, everywhere in the world as far as I know.
They often pay the state more than citizens (because of various substantial fees, every year in some countries), while receiving less for it.
It breaks my heart, to think anti-immigrant sentiments may be helped along by such misguided beliefs.