From the start of a summery of A New Hope:
I don't think Obi-Wan ever meant to confront Luke. I subscribe to the notion that the whole thing was an elaborate trap to lure Darth Vader there for a final battle to the death.
He takes Luke there as a child, doesn't even change his last name to anything other than Skywalker, and leaves him with Vader's mom's family on a sparsly populated planet so there's no over abundance of life to hide the kids force talent which is sure to manifest. Then he just sits there in the desert, waiting for Vader to show up so they can throw down on a hardcore force battle in a desert where there won't be much collateral or many opportunities to take hostages. Only he never shows.
Years go by and Obi-Wan is starting to get old.