The noun next door is a decoy
who is really the subject?
The verb belongs to the real subject, and that is often not the noun standing right beside it.
The cost of the new tickets aresubject 'cost': use 'is' rising, and one of the routes have'one' is single: use 'has' fewer trains. Nobody know'nobody' is one: 'knows' why.
Fixed: is · has · knows