I'm not talking about bans from sites.
Do bans work on guns? Do bans work on alcohol (the US went through Prohibition from 1920-1933). How about the ban on drugs?
Do you mean
1) Are bans effective in the sense of total erradication of a product
or substance?
or
2) Are bans effective in limiting a product or substance?
If you mean (1), then no. As long as demand exists so will prohibited
substances and products
If you mean (2), then it depends. Some substances are easier to
obtain as it is as easy as growing them (for instance tobacco and Cannabis
and other plants that are limited or outright banned by governments).
Some substances are harder because they require special skills and
equiptment to produce (like LSD or certain pharmaceutical substances).
Some products are even harder as they likewise require special equiptment
to manufacture (such as firearms and bullets), however the availability
is proportionate to the amounts already available in the marketplace, and
how long they have been.
Among what you listed, alcohol is by far the easiest to obtain. It can
be made out many different plants, not just fruit and sweet plants. A little
more knowledge is required for producing it out of non sweet plant material,
but it is not beyond the ordinary man's reach to do so. This is why I laugh
at certain Muslim clerics and their fantasy ideas of implementing an alcohol
free society by "limiting fruit for a while". Don't they know that a substancial
amount of alcohol made during the US's alcohol prohibition was
from grains and potatoes?