I would actually question this - I used to show my dogs and have had both show and working lines in my breeds (gundogs not terriers). The working line breeders would put a steady temperament above looks, the show people are more likely to breed from a nice looking dog anyway. Working dogs have to be able to jump in the back of a car, mix with strange dogs and people, and not bat an eyelid
I’m not so sure.
I definitely agree that a show breeders goal is the next champion so temperament is often not a priority and dogs with excellent confirmation (but not so solid temperament) may be bred when they really shouldn’t be.
I have a working bred dog myself and I wouldn’t buy the show bred version of her breed.
But a working gundog and a working terrier are two entirely different beasts.
Gun dogs do indeed have to work with other dogs and large amounts of strange people.
They also work actively with people, awaiting instruction from their handler to go and retrieve the game.
But working terriers (as I understand it) work mostly alone both as in working with one terrier and not a group and working independently with little, if any, instruction from their owner.
Their job is to find rats, rabbits, foxes etc and go and kill them.
Working terriers should have a sky high prey drive, they often are very stubborn and not very handler focused and a large proportion of them are very dog aggressive and won’t back down in a fight, literally fighting ‘to the death’.
Many terrier breeds have been ‘watered down’ over the years, the Patterdale/Fell terrier is one of the only ones left that is almost exclusively bred for working and in pet homes people often seriously struggle with them.
While I am generally opposed to the breeding of ‘show dogs’, the idea of breeding to a specific ‘look’ and watering down a breeds instincts and traits, I do feel that working terriers are one group of dogs that really are best placed in a working home.