I had three balls lost in my last few rounds this year.
One ball I pushed it a little right towards the trees.I search and found like three balls but none mine.So I play the provisional.Then,like ten holes later a guy in my group putt a ball exactly the same as mine .He told me it was his,he found it during the round.He was a good guy,so I was not sure.
A week later,same thing,a guy in my group putt a ball exactly like mine at the 18th after I lost one like that at tthe 3rd.It was his only one like that,he found it at the beginning.Again,none tried to see if it was mine and I couldn't claim the ball.Now,I mark them,can't believe people steal partners' balls.