Technology is very useful for people’s life.

1. People
We assume you’re making statements about people, and not animals or aliens, unless otherwise stated.
- Chocolate is delicious.
(= chocolate eaten by people!) - Driving too fast is dangerous.
(= dangerous for people!) - Urbanisation causes many problems.
(= problems for people!)
OK, so you might argue that urbanisation also causes problems for wildlife, but if you don’t mention wildlife then we assume you’re talking about people.
2. People’s lives
(In our opening example there is a grammatical error – people’s life. ‘People‘ is plural and ‘life‘ is singular – so it doesn’t make sense to put those words together!)
- Chocolate is delicious.
(= at any stage of life, as long as you’re alive and not dead!) - Driving too fast is dangerous.
(= at any stage of life, as long as you’re alive and not dead!) - Urbanisation causes many problems.
(= at any stage of life, as long as you’re alive and not dead!)
Again, it is assumed you are talking about people and the things that they do while they are alive and that these things affect their lives in some way.
3. When people and their lives DO matter
- Chocolate is delicious unless you’re dead.
Why anyone would want to write this, I don’t know, but if you’re not alive you obviously cannot enjoy chocolate! - Driving too fast is dangerous for animals living in forests that have roads passing through them.
It’s a problem for animals, not people. - Urbanisation causes many problems for aliens trying to land their spaceships.
Again, I cannot imagine anybody needing to write this, but these are problems for aliens, not people.
4. Similar problem words
Students experience a similar problem with the word human (dealt with in a this post and this post). Again, you only need to mention humans if you’re contrasting them with other species or with aliens!