What other reason could there be for Trump not providing any evidence?
Complexity lies in more than just that question.
The accusation might have a firm foundation or a speculative one.
And as we see, government is spying on a great many of us.
We should expect Trump & his associates to be included.
Obama's involvement might be direct, or as one who sets policy,
& not even aware of the details.
I sense that many people who loathe Trump are very hopeful that
his accusation of Obama wiretapping him will lead to his downfall.
They imagine how it
could happen. But it looks really unlikely.