In effect, that's what's happening.
The rescue/recovery is being led by the US Coast Guard, supported by their military and the Canadian Coast Guard and military, and various deep sea specialist companies, oceanographers etc
I don't think you appreciate the distance they are from shore (and how long it would take assets from elsewhere to even reach the likeliest search areas)
Nor how very limited are the options for what you can do if the vessel has not surfaced independently.
What would cause the lack of pings? Defer to the experts, but the possibilities include failure of the "pinger" (can resurface normally, but no-one knows where it is to retrieve - this is the best case option, because if spotted in time, it would be possible to survive), complete power failure (might make it - slowly - to the surface, reducing window to be spotted and retrieved), trapped (by getting to close to the wreck, or something like a ghost fishing net, some of which are huge), or catastrophic failure (pressure down there is immense and breach of the vessel would mean instant death by crushing)