I don’t know why people are fixated on them not finding CCTV for ages. He wasn’t reported missing until Weds night, the locals didn’t know until Thursday.
As someone else pointed out, many business owners don’t live on Symi, they commute from Rhodes in tourist season. It is not surprising that people didn’t check footage until later on Thurs and Fri when word got out he’d not been found in the most obvious place.
At the end of the day his wife and friends presumably told police his plan was to walk the short path to town then catch a bus. It’s not surprising police focussed on where he should have been, rather than through a rocky and desolate hillside.