You need to pursue alternative players and make power sellers believe you are not going to buy your main targets, so that they will be more accommodating. Come on, it is not rocket science, Marotta is pursuing Danilo, Aurier, Darmian, De Sciglio and Spinazzola in order to buy Danilo for 15m euros or De Sciglio for 5m. However, your business not my business, United have the money and can merrily pay whatever you are asked for.
Pursuing vs buying are different. My answer was to the poster who suggested we buy (actually, buy) Vardy and Ox to pressurize Real and Inter - despite it being clear that:
1. We are pursuing other players - we've been linked to at least 30 this summer, if not more
2. The selling clubs clearly not wanting to sell
3. Every English club being asked to pay a massive premium given their riches from the TV deal
4. These alternatives being so sh*te as to be meaningless as pressure tactics
5. The economics still making absolutely no sense
Inter, Juve and co. are working differently because - wonder of wonders - they're different clubs with a different reality. Man United are in a weak position, specially when it comes to Real and Morata. Real clearly have no need to sell. Even if they were to buy Mbappe for a ludicrous amount, this is a club that's almost as rich as United and has players like James that they can offload for high amounts anyway. Oh, and they don't need to sell to fund a move, since they don't have such glaring holes in the squad. Plus, Morata is a striker they'd love to keep. He's not on insane wages, is lethal when called upon and is young enough to not be past his sell-by even in a year's time.
It's not rocket science to know when a seller holds all the cards. In this case, if we were to tell Madrid we won't play ball and will sign Vardy instead, I think I know which side would be laughing...and no, it would not be United.
On Perisic - you may not rate him (I do, actually) but Ox? Really? It's like me threatening BMW that if they don't reduce the asking price, I'll buy a fecking Smart instead. Hardly likely to work, I think you'll admit, specially when (once again) it's not clear that Inter don't need to sell and are quite happy to keep Perisic (I recall reports which even said that when Spalletti signed, he said he wanted to keep Perisic).