Is it polite to ask the opponent to resign a lost position?

I haven't frequented chess.com for a couple of years, but my boss suggested that i should play those 3 day online games. So now I am back at chess.com. Lost the first game, but now I am playing two simultaneous games against someone who is in clearly lost positions against me. For some reason, he does not resign! I consider it a matter of politeness to resign when it is clear that you have lost. I resign when I am a pawn down without clear compensation.  I know I cannot force somebody to resign who is playing on in the hopes that I have forgotten about endgame basics that primary school kids know, but would it be too harsh to ask somebody to accept the inevitable? 

To the title: no. To the question on the post: yes.

Btw, some K+P vs K endgames are a dead draw.

No. The definition of "lost" varies widely. Sometimes lost means a certain win, but the opponent simply does not see it. To me lost is the past tense of lose, meaning a lost game is already over, so there is obviously no need to resign since the game has already ended in a win (or loss). Other people think lost means a position that is likely to result in loss. But that doesn't always happen so it's really a losing position, not a lost position. I have been in what some might consider a "lost" position down a queen and a bishop, facing a checkmate in one with plenty of time left. Yet my opponent still managed to find a stalemate. It quickly went from a lost position to a losing position to an equal position. All in one move.

Why do you ask your opponent to resign? Resign for him!

Obviously. I don't talk about such positions. I talk about those where the outcome is clear to anyone who has ever looked at a book or a website about endgames. I expect that from people who are rated higher than I am. I am certainly not a good player. 

I would not ask someone to resign if there still is some play and uncertainty like in your example. I think if a kid in the first year of primary school tells me that the white player will certainly win then a player rated 1700+ should understand that as well. 

I think it can be asked without being rude, especially if you provide the reason, such as your next planned moves, and why counter-play is hopeless. Your opponent may actually appreciate the calculation (and he has the option to try to refute it).

(fyi: I play slow play variants)

On the other hand, an opponent has every right to keep playing until checkmated.

I was once in a hopeless position at around move 90, but kept playing just because I was curious if I can last to make it a 100 move game.😊

Of course they will understand it, and they will probably also understand that EVERY position (except checkmate and stalemate) has uncertaintyBut sometimes positions are complex, and what you think is a winning position for you is actually a winning position for your opponent. Sometimes 1700 rated players simply don't see it. In my example all my opponent had to do is checkmate me in one move. But he didn't. Instead he made a different move, resulting in stalemate. Of course I could have resigned since I was in a losing position. But I wasn't in a LOST position, the game was still in progress. As RookSacrifice said, he should have done the resigning for me.

You don't ask your opponent to resign. They're entitled to play to mate. 

I also think you're being a little inconsistent, because you say both:

"I resign when I am a pawn down without clear compensation," AND " I talk about those where the outcome is clear to anyone who has ever looked at a book or a website about endgames," AND "I would not ask someone to resign if there still is some play and uncertainty like in your example."

Being a pawn down, even for absolutely zero compensation, does not mean that the position has no play, or there's no uncertainty. There are lots of interesting tricks which can be played even in very simple endgames. 

I've outplayed many opponents from positions when I was a pawn (or more!) down. 

It's entirely reasonable for your opponents to want to see you prove that you know how to win the resulting position. Maybe you'll make a mistake which will let them back in the game. 

Never, ever.

Only if you are familiar with that player.

(in the event he agrees to a post game analysis, you could drop the question there)

Nope. Just keep enjoying the winning position as long as it lasts

once got a opposite coloured bishop game each players also have one pawn left- offered a draw 

declined 

asked himorher how on earth he/she wants to win this - of course game struggled another 2 minutes

Is this unfair to ask sth like that? 

This is kind of the situation I am talking about. I don't think it is unfair or improper. In my case I am playing 3 day games and it seems like a waste of time to drag something out that has already been decided. 

you know that scene from the film pawn sacrifice where fisher announced an unavoidable forced mate to his opponent because he was tired waiting for him- kinda unpolite too lol

Try and think of online chess the same as OTB play.  You dont lean over the table and ask your opponnet to resign.