I think the usage of the word also depends greatly on the context in which it is used.
For example ,
The industrialist controlled all areas of his business. ( meaning the company owe by a person )
A woman has to manage all her businesses, looking after the house and the office. ( meaning different tasks undertaken )
All businesses use the same corporate stratergy to grow. ( meaning differnt enterprises )
Any comments on the above or futher examples to clarify this .
Regards
Aster