Rules often change to reflect current trends (not always a good thing). It has now become more acceptable to write "businesses" purely because of asthetics and to reflect the more common pronounciation.
Regarding people's names, if the name is naturally spelt with an 's' at the end for example "Jame
s", then you only put an apostrophy ( ' )
without another "s" so the plural of James will be James
' not James
's. However, just to be difficult, it is acceptable to write "James
's" when continuing the sentence, for example "We visited St. James
's palace". As with "businesses" this was introduced for asthetic reasons.