Most house locks are trivial to pick in about 30 seconds, and what I've seen of "smart" locks isn't much better. I think if you were really serious about preventing intruders (rather than discouraging opportunism) you need alarms and cameras and someone with a big stick.
How about having some actually solid walls and doors first instead of the cardboard-like materials of many US apartment buildings?
I do wonder how well that works (for y'know, not being fire hazard and not being terribly insulated, being able to whither bad weather conditions, ..).
I have not visited their new place yet so I can't comment on what it is like to live there. But houses in Europe just look more sturdy.
That is one thing that makes me think investing in housing in the US is a bad choice. The houses just don't seem like they are build to last. (Again I am judging it just by the looks and I could be completely wrong about it!)