There is a cottage industry of taking books and or manuscripts that are in the public domain and re-packaging them for sale. Sometimes a great deal of work goes into translating such works that are in a different language to English and sometimes it is just a matter of loading the archaic text into Microsoft Word and using the grammar and spell checker to update it to modern English. A bit of formatting and an AI generated cover and you have an eBook. What you are paying for is the convenience of having the work done for you. Much like paying someone to deliver food to your home when you could go pick it up yourself.