White normally accepts gote to live here in this way.
Tamsin: More on this position: White can live in sente if she plays at b, but this is usually a bad move. The point is that after 9 in the diagram, she may end in gote, but she has the aji of cutting at a. But, if she plays at b, forcing Black to respond at c, then the cut at a is no longer very useful because even when the ladder is good for White, Black can still capture with a net. Moreover, Black has the option in the endgame to take a large capture at 9 in sente, reducing White to a tiny corner. So, White would only play 9 at b if there were really pressing reasons to do so, because in this case the aji is normally worth more than sente.
Charles Yes, much the same is said at 3-4 point low approach one-space low pincer, tenuki.
If White comes in on the fourth line, Black connects under with and White cannot break through. The attraction of this enclosure is that it is the maximum extension from the 3-4 point that remains connected.
Example moved to wedge - when the approach is possible.