Sure, you shouldn't ignore this, but that just makes it automatic. Both (or all 3, 4) players will try to get 3 more coppers in their deck, and if there's any sort of +Buy, this is pretty easy. If there's non-terminal +Buy or a very nice engine, it's trivial to just get this at the end of the game, especially if you're the one ending it. If you're not ending it on some megaturn, then you need to make sure you have the 10 Copper before the other guy ends the game -- this acts kind of like a quasi Distant Lands type of deck, where you need to buy and play those VPs before the game ends and that was a total waste of time (but unlike DL, there's no 'split' to win). In a large slog-type of deck, getting three Coppers before the last reshuffle isn't that big of a deal.
So, if it's fairly given that both players get +15 VP, the better question is, how easy is it to win the splits of all of the other VP with 10 Copper in your deck sooner rather than later? This will nudge you towards playing with Counting House or Coppersmith. I think Apothecary is strong enough on its own; Fountain just makes it more obvious.
More interesting if there's no +Buy or very good trashing. If there's Chapel or some other great trashing on the board, perhaps this is a rush between the player who intends to go for Fountain and the one who tries to get as many Provinces as possible to offset it. If you win the Province split 6-2, that's 36 VP. The other guy will have 12+15 = 27 VP, or possibly 30 if they didn't trash estates either. That could be a tall order, especially if there is an easy way for the Fountain player to spike Provinces (like Beggar or Baron).