Sale of non-transferable tickets

aro68

How is it possible for companies such as Seatwave and Viagogo to sell tickets that are non-transferable?

This is the first time that I have used an on-line ticket resale company to purchase some last minute tickets for a sporting event, only to find that one of the Terms and Conditions of the original tickets is as follows:
"Tickets purchased are strictly non-transferable and are for the sole use of the purchaser. Tickets may not, under any circumstances, be auctioned, offered for sale or re-sold in any manner and should not be purchased or obtained from or through any person, commercial agent, company or by any method other than directly by the applicant from *****."

It seems not only have I done wrong in purchasing the tickets, but also that they should not have been offered for sale in the first place. How do these big ticket resale companies get away with doing this legally?