In the U.S., my son is usually used as a term of respect by an older person for a boy or younger man. There is an element of the speaker reminding the other of his/her seniority. If the two are close, it could be considered a term of endearment. The two don't have to be members of the same family.
I'm not sure how long it has been around, but I suspect a long time.
Is there really no equivalent in German?
3) will for present habits:
There is no question that the verb (or verbs; there may be several) will is one of the very trickiest ones in the English language for foreigners ever to master. The deontic senses are seldom intuitive to a non-native speaker. I strongly advise you to carefully study the OED’s entry for this word’s incredibly many subtle uses.
In this case, your two examples are not of the same thing at all, and you have mischaracterized them. The first uses will to express habitual action; it does not indicate a simple future situation. This is the OED’s sense 8 for this verb:
8. Expressing natural disposition to do something, and hence habitual action: Has the habit, or ‘a way’, of ––ing; is addicted or accustomed to ––ing; habitually does; sometimes connoting ‘may be expected to’
This is related to sense 15, which is still not a simple future, albeit perhaps closer to that:
15. As auxiliary of future expressing a contingent event, or a result to be expected, in a supposed case or under particular conditions (with the condition expressed by a conditional, temporal, or imper. clause, or otherwise implied).
Your second example, the one about the car, is completely different. This corresponds to OED sense 12:
12. With negative, expressing the contrary of senses (def#6), (def#7), (def#10), (def#11): thus commonly = refuse or decline to; emph. insist on or persist in not --ing. Also fig. of a thing. (See also (def#9), (def#13).)
Here, your car is persisting in not starting. It is the figurative sense at the end extending to things, as though they had the will to refuse. The referenced senses 9 and 13 are respectively:
9. Expressing potentiality, capacity, or sufficiency: Can, may, is able to, is capable of --ing; is (large) enough or sufficient to.
15. As auxiliary of future expressing a contingent event, or a result to be expected, in a supposed case or under particular conditions (with the condition expressed by a conditional, temporal, or imper. clause, or otherwise implied).
As I said, will is quite complex. Please study standard reference works regarding its use.
Best Answer
It's informally referred to as a parenthetical read (also discussed here).
In some contexts, it's a form of videlicet.