Haaland decided to join Borussia Dortmund from RB Salzburg in January, snubbing an offer from United.
"You never know how it would go in other clubs. It may well have been good, too," he told TV2.
"We'll never get an answer to that. But we are very happy with the clubs he has been in.
"You have to go to a club where the whole club wants you, not just the coach.
"I think that's the most important thing, in addition to how the club has been over the last five or ten years and what direction they've taken."