I wonder how much of the phenomenon is historically based on past actions of unions. Regardless of class there is no intrinsic virtue to station and the incumbe

I wonder how much of the phenomenon is historically based on past actions of unions. Regardless of class there is no intrinsic virtue to station and the incumbents would be incentivized in the short term to keep newcomers out to inflate their guild's value. Doing so without a legal monopoly however sows the seeds of their downfall as they lose the critical mass of labor needed and going with the cheaper newcomers becomes not only viable but preferrable. Long term said maltreated former newcomers would be left with negative experiences towards unions and likely think of them negatively. That scenario has echoes in the past well before industrial organized labor and guilds into outright caste dynamics - although those may occur from lack of an educational infrastructure leaving occupation essentially heritable and it being codified.