Owen Lars never understood it. Every time Luke snuck out to go bother the old hermit, he'd had to fight the urge to chase after him hollering. He'd done that so many times already. He was hardly proud of that.
Luke spread some pretty wild rumors about Old Ben, mocking a legacy that barely existed on Tatooine. What was the point? Everyone had at least heard about the Jedi, the Empire, but on a world dominated by the Hutts and basic survival in a landscape that didn't want inhabitants, such stories only served to remind Owen of something he'd just as soon forgot.
The last time he saw Luke's father, the wild adventurer Anakin had been friends with Old Ben. For all Owen knew, that was the only time the Skywalkers and the Kenobis ever got along.
Stories about the feud between those families were far more common. Anyone who knew Luke knew he was always eager to share them. Some of the people Owen knew thought the whole thing had sprung entirely from the young Skywalker's eager imagination. Every time Beru cautioned Owen to give Luke a little slack, he could only picture the time the boy had plastered their entire home in fake lightsabers, none of which, of course, functioned, which was what Luke claimed was exactly the case with Old Ben's.
The longer this went on the more exasperated Owen became. When Luke's pal Biggs Darklighter entered the Imperial Academy, Owen had to put his foot down, mostly because Luke was already making a mockery of the whole application process, putting Old Ben down as his sponsor, when everyone knew that the hermit was a terrible public speaker, couldn't hold a conversation, and it was probably only partly due to the constant stream of torment he received at Luke's hands.
The worst of it was that it was Luke himself who told Owen that it was a tradition between the families that he was only continuing, to the point where Owen questioned whether his own memories were an accurate portrait of the past.
When the Empire finally came to Tatooine, news quickly spread about the two most immediate results: that Owen Lars had been murdered by Stormtroopers and that Luke had gone off with a couple of droids in the direction of Old Ben's desert hut, the action that led directly to Owen's death. It came as no surprise when the hermit was also reported as dead, lost in the grand space adventure Luke had spent all the time he wasn't mocking Old Ben talking about. Some speculated that the droids had led Luke to recruit the hermit, validating all the old stories. Others pretty much assumed they knew what had really happened.
Luke, as always, was just being a punk.