So what? Other managers have done the exact same under harsher circumstances. Just because United haven't doesn't mean that's the norm.
The ability to win the double? What if he fails to win anything again? His time at Liverpool is still yet to be marked by a trophy. I'm personally prepared to wait on the parade till he actually brings some silverware home to mark his time there. It's not like he is Pochettino, who has to work under genuine constraints, if you spend 170m in a single summer you should be expected to win trophies, not just get close.
I wouldn't have laughed at you had you told me Liverpool would be a success under Klopp. They brought in one of the world's top managers and then backed him superbly well in the transfer market, shock horror as he then does well.
He sold one of their best players. And it's hardly rocket science that they needed to sign a CB and a keeper.
Klopp is doing nothing that any top manager wouldn't do at Liverpool with big resources at their disposal. The potential was always there at the club, they just needed a top coach and then needed to give him genuine money, which they have. I don't see the need to romanticise his work there, he was 4th and not winning shit all until the spending started pouring in.
You do know that before klopp signed VVD, Alisson and Keita. Liverpool's net spend under Klopp was negative. I.e. he had made more money from players sales than he spend. Only reason he went big was because he had the funds and he had to replace his star player. Spurs got lot of money when they sold Bale, i didnt see your managers "doing what is expected from any manager."
Now lets compare Man City and Liverpool.
Defence :-
Liverpool :- TAA, Matip, VVD , Robertson and Alisson = £ 150 Million
Man City :- Walker, Stones, Laporte, Mendy and Ederson = £ 243.7 Million
Midfield :-
Liverpool :- Milner, Henderson, Wijnaldum, Fabinho and Keita = £ 135.4 Million
Man City :- Fernandinho, Bernado Silva, David Silva, KDB and Gundogan = £ 199.58 Million
Attack :-
Liverpool :- Salah, Mane, Firmino, Shaqiri and Origi = £ 136.38 Million
Man City :- Aguero, Sterling, Sane, Gabriel and Mahrez = £ 228.60 Million
Liverpool = 91 points in 36 games with squad cost of £ 421.78 millions
Man City = 89 points in 35 games with squad cost of £ 677.88 millions
(Note :- The list above is composed of players which have featured regularly for both teams, if we add the value of all players, the gap will only increase.)
So now based on stats above if Klopp is doing what is expected of managers then is Guardiola underperforming?