They are wrong, though. Locks also stop people who would happily commit an opportunistic theft but who lack the necessary tools or skills, people who would tres

They are wrong, though. Locks also stop people who would happily commit an opportunistic theft but who lack the necessary tools or skills, people who would trespass if they could retain some plausible deniability ("oops, I didn't see the signs" vs. "oops, I didn't realise I wasn't supposed to cut that padlock"), and so on.