Vardy, Sturridge, Kane has 0 goals in PL so far. Rooney and Sterling doesn't play in his position. Defoe wasn't in the last English squad.
Alternatives of Hart are Forster and Heaton who are starting regularly for their teams and doing well.
TBH I couldn't care less about ENgland
Vardy, Sturridge, Kane, Rooney and Sterling are all established internationals. All fit. All playing. All capable of playing across the front and therefore in direct competition with Rashord. Rashford had an impressive 5 minutes against Iceland wide left and looked lively in the shield for 15 minutes, wide left.
Joe Hart whilst over-rated is also an established international and better keeper than Heaton and Forster.
It's fairly simple really. Take your tinted glasses off.
As for United, Rashford will get his game time. How much will depend on him.
All young players at big clubs face the same situation of having world class experienced players ahead of them. If they are good enough, they'll force there way in. If not, they'll be sold to Everton or Sunderland.
Personally I want the club to be successful over giving pampering to kids and playing them just to develop them. We are one of the biggest clubs in the world, not Southampton. If they are good enough they'll play but as the cliché goes, no one player is bigger than the club.
I had this argument when we signed RVP. People didn't want him and would prefer to "give Welbeck his opportunity".
This year....Zlatan starts in the Premier League 38 games he'll get 25 goals and we'll likely win the league. Rashford learns, contributes goals off the bench and in cups.