It is an interpretation, the Copenhagen interpretation. There are other possibilities and nobody knows the real ground truth yet. All our speculations are just that
After almost a century of discussions between smart people, the physics consensus has steadily inched away from Copenhagen.
That said, that doesn't mean lazy evaluation isn't happening. You just can't use lazy evaluation to "explain" wavefunction collapse, it's more the other way around, that collapse can be a lazy evaluation trick. It'd describe only this simulation and say nothing about outer reality (thus no longer works as evidence for or against the simulation hypothesis, it's just a consistent part of the story given that it's true).