The owners of these shops are looking to be seen online and get solicited constantly by these shady “agencies” offering all kinds of pie-in-the-sky results when they sell the service but deliver very little in practice. 80% of what they claim they’ll do (and then don’t do at all) could be accomplished in-house with just a little knowledge and effort.
Search Engine Watch
Search Engine Roundtable
Backlinko
Niel Patel
These are all SEO blogs from experts in the industry.
The fundamentals are always the same but the more advanced and modern tactics are ever evolving.