Oh dear - raw nerve touched here (I paid nearly five grand for a new
block-paved drive and front garden path last October and still have some
drainage 'issues' to resolve).

On the basis of my experience: if left unsealed it seems that block paving
does indeed allow very good drainage from the gaps between the blocks. None
of the reputable companies I had to quote included sealing in their quotes.
But you need it to stop oil etc from staining the blocks - and I think to
stop weeds growing up in the gaps. I wasn't able to apply sealant to my
drive until April, six months after it was laid. But it immediately showed
up several problems of insufficient drainage. The installers fixed most but
not all - we're now in dispute.

So...yes I think you need a proper fall and drain arrangements, and to bear
in mind that even when you have these you will need to seal or have sealed
the drive before you can judge how adequate the installation is. The fall my
drive installers looked excellent, even over the top, but wasn't the end of
the story, as I've explained.