Hi,
Region: many countries/regions have their own safety regulations.
Application: safety regulations also depend on application, like: commercial, industrial, aerospace, medical... but also: plastic case vs metal case ... and also: functional isolation (in the meaning to avoid arcing and fire) or protecting isolation (in the meaning to protect humans against electrical shock)
Environment: humidity, temperature, pollution..
It´s a wide range, thus there is no "general answer".
In your case: phone chargers: = Commercial product, indoor use, plastic case....
-> I assume the wire just needs single functional isolation. This usually is what you find on the wire´s datasheet.
Yes: every wire from every manufacturer comes with a datasheet. The manufacturer needs to provide it. (if he does not, then don´t use this wire)
Wire manufacturers will also provide additional informations. Look at their internet sites.
Klaus