Standardization is a fairly new concept. The whole premise of there being only one or two things that make an herb work or make a person sick is the basic weakness in the medical profession. Synergy happens and the combination is best left to the plants' wisdom without interference by arrogant humans who think they know better than their Creator. So, sometimes we have to bow to the will of the majority, even if we don't agree. If you've never been in a health food store before, you may be surprised at how many different forms the same herb can come in.
Tea is the most common and oldest form of herbal therapy.
However, beyond the fact that many both taste and smell terrible, many herbs will not give up their goodness to a cup of boiling water and need more vigorous methods of extraction. That's why there are alcohol extracts and, for children and recovering alcoholics, glycerin extracts. For digestion, calming nerves, general feel good, I choose teas. The herbs for these areas of life are pleasant tasting and the combinations made for specific problems are specially blended to taste good. I've had customers report feeling a lot better with teas blended for breathing freely whether for bad coughs or allergies.