dried spices and herbs fill a niche and here in the USA can be found everywhere that sells food... and that includes what we call dollar stores...

and it's a sad fact that in spite of being a wealthy country, that wealth does not reach down to many people who live virtually hand to mouth...

without transportation, many live in cities and have little access to fresh produce, etc.... and packaged processed food needs all the help it can get

I grew up with dried garlic and onion powders along with various Italian dried herbs... when used in cooking it works just fine and is very cost effective and time saving for the cook who might have plenty of other things that need doing