One thing to remember, Boston is only a seasonal port. There is no reason for USCBP to install facial rec, etc due to this. Also, the bulk of the sailings are Canada/New England or Bermuda. Also, the port itself doesn't have much space. I believe the one time I had to pass immigration in Boston (it's been quite a few years) they actually came on the ship for inspection as you got off. The last couple of times, I was on a cruise that stopped at Bar Harbor so we had to inspection there (they come on the ship, you can't get off until you are cleared).