Did you use the stats from "Transfermarkt"? Because they count won penalties as assists. But you could argue that a won penalty is as important as an assist. Rashford won 2, Salah 0.
But even crazier when you look at the stats without penalties scored.
Salah with 27 G&A (22G, 5A) this season. 14G+4A in premier league without penalties in 2722 minutes. +0 penalties won.
Rashford with 32 G&A (19G, 13A) this season. 10G+9A in premier league without penalties in 2786 minutes. +2 penalties won which you counted as assists.
So without penalties (Salah scored 7/7, Rashford 1/1) the stats are definitely in favour for Rashford. He can be a bit frustrating at times and his form is not great right now but he gets far too much shit for his performances. Former academy player, good lad and plays on a very high level. Still does get so much shit...