No it really isn’t. Small 100g samples for example aren’t available (anymore) because it would only give the user one attempt to try the product. I didn’t like my first Huel powder shake. It took a few goes before I got the ratio of powder to water, my preferred flavours, how much flavour, chilled/ambient water, left to soak or freshly made, blend in fruit or other stuff, and simply to get used to it. There are literally hundreds of combinations on how to make a shake. If you only sell a one shot packet and the user doesn’t like it you’ve lost them forever. If you sell them a whole pouch they can have a few tries changing the factors above before making a final choice.
Buying a single bag though should be possible but it’s not because of legacy website design choices. Work is being done at the moment to offer some flexibility here, hopefully allowing people to get hold of a single bag easier, but we’ll have to wait and see what is changed.