Google didn't previously own the map data (Tele Atlas did and they're owned by GPS device company, TomTom) so it wasn't theirs to license. They only recently started using their own maps earlier this month for the US.

Also, Apple recently acquired PlaceBase so they now have access to their own map data.

There has been a change. Google used to license map data from a 3rd party for web display, now Google is increasingly making their maps from original sources. I just checked and the turn-by-turn prohibition is still in their terms of use, but one could imagine that when the data is all Google generated and owned they could lift that restriction.