You talk about tier system. Well I hate to say it but union contracts do the same thing. I have work at union shops. The one shop had 2 tiers. The other one had 3 tiers. In the contract they call it hired before dates. Yes the benefits and pay were the same, but when it came to holidays, and vacation accrual that were the difference was along with some other stuff. Their were holidays I was working at straight time while some, if they chooses to work got holiday rate. I also have a friend in a union shop that has 3 tiers and his deals with pension and healthcare and reinterment benefits.
You can sit there and call out XPO for this but the unions been doing it for years.
If you don't believe me then why does UPS have a facial hair in the contract. If hired before this date you can have facial hair and everyone after that date can't.
Yet the union preacher fairness and that everything is the same for every employee in the same job title, but yet they do this.