The upper class has been wearing expensive jeans for a very long time.
The upper class doesn’t need dress code. They know they are the upper class. Dress codes are for petit bourgeois and the upper middle class who try to pretend but everyone knows they are actually middle class.
>>Random+(OP)
The upper class, however, seems to care about making other people follow a dress code. Think uniforms for a chauffeur, the long-standing rules around wearing white at Wimbledon, etc.