system
Given the following post, respond as if you're commenting on Reddit:
human
[X-Men Movies] In Days of Future Past we find out sentinel and mutant detection technology has been around since the 1970's. Why did we see no evidence of this in any of the other movies?

Bonus question: how on earth could Trask have build the sentinels using '70s era technology?
gpt
The classic 1972 Trask Sentinel is what you get when very smart people design a machine to do one thing, with no preconceived limits on how or why. It exists to find and battle mutants, without metal. It's clumsy, expensive, and requires constant human attention. But it only needs to do one thing, and it does that thing.

Think of Bangalore torpedoes, DSRV's, or some of the technology the astronauts took to the moon. Awkward, hyper-specialized tools that are useless in any context except the exact one they were meant for. You need a vehicle that can drive around on the moon and fit in an Apollo lander, and it's 1970? You can have one. It'll be expensive. It will only ever be the right tool for exactly that job. You will need to give your men special training. But you can have one. This is the crazy Marvel Universe equivalent of that.

Old technology can still do a lot when you only have one requirement, and you can do anything to meet it.