I don't think we can say it that decisively. Only for individual situations. So, in this sentence, yes, it is transitive.
Just like in English:
I am waiting - intransitive
I wait until tomorrow - intransitive
I wait for you - intransitive
I am waiting the results of the test - transitive
I am waiting for a chance to strike - intransitive
I wait tables at a restaurant - transitive
It is pretty much the same with Hungarian. It depends on the situation.
The above sentence could also be:
"Az ügyvéd egy fiúra vár." - "The lawyer is waiting on a boy."
And, "Az ügyvéd egy fiút vár" could also mean "The lawyer is expecting a boy". And there you go, both the Hungarian and the English used the accusative.
So, it is complicated. :)