The same can be said about Flock, or other surveillance state mechanisms.

It's good for security, it's more convenient than police doing police work.

Until it's not. Until it's hacked or abused as powerful mechanisms commonly are.

There's some level of difference to be fair

Hacking is a concern in both but the bigger issue is potential for abuse of power.

In the case of border checks the target is by necessity someone that isn't a citizen. This means that:

1. We generally afford them less safeguards than citizens so it creates less precedent (both legal and in terms of overton window)

2. The potential for abuse is ultimately less because a traveler on a short term visa is unlikely to still be in the country / unable to leave if a hostile government comes to power and intends to abuse the data

Also fingerprints and a picture are significantly less invasive than pervasive video surveillance in public spaces

Some amount of surveillance leads to a better society. See SG. Flock is needed for current USA. That's why idiots are up against it.