Home made bottled kombucha tea is the best and safest way to drink kombucha tea.
Kombucha Tea is a natural probiotic drink. You don’t want it to be pasturised or heat treated at all or it will kill the probiotic. A new culture will form at the top of the bottle if it is indeed still raw. This means that you will receive all the medicinal benefits from drinking the tea.
If you buy bottled kombucha tea and there is no culture forming at the top or the liquid is totally clear, then it is not raw at all and you will not be getting the health giving benefits from drinking the tea.
I may be wrong, but my family have been brewing kombucha for as long as I can remember and there is no way that a kombucha tea will not form a culture unless there is absolutely no sugar left at all. A good test would be to buy a bottle of your favourite Kombucha tea and pour it into a container with some standard tea with sugar and see if it ferments and forms a new culture or scoby.