single flights and return flights

[needadvice:)]

Firstly why are single flight tickets more expensive than return tickets? and secondly what is stopping anyone just buying a return ticket with no intention of returning?

[kwd1954]

Just a marketing ploy to get you on same airline back. My wife bought a return from Glasgow to Gatwick with no intention of taking return flight but it was cheaper. (She was driving back - not that she had left me !!!)