Hello Inbox

I would hyphenate some of your examples slightly differently:

1. real-user movements (because the phrase 'real user' is here used attributively, as an adjective).

2. user movement (I wouldn't hyphenate here either).

3. I have studied the user movements on the college campus over a period of three months. (Nor here.)

4. A reckless car owner.

5. Many car owners neglect etc.

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As a general rule of thumb, I would hyphenate:

a) where there's a real chance of confusion ('a deep-blue lake', where 'deep blue' is a colour; a 'pink-spotted handkerchief', where the spots are pink);

b) where a phrase is used as an adjective ('a rule-of-thumb generalisation');

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That said, there doesn't seem to be a standard practice among publishers or copy editors for hyphenation; and no doubt many posters will disagree with what I've written here!

MrP