Typefaces and the font-families for distribution are like cars. There is never a right or wrong. There are "better" brands with better quality and/or more features. But some customers would define a more expensive car as a "worse" car because they just want "a chair which moves them from A to B", not a living room with an 800$ stereo and coloured carpet.
If different companies like Google or Adobe decide to bundle different packs or some websites let you pick and download or licence individuals weights or whatever then rejoice: all it means that you got choices. There is no danger, there are seldom hidden traps, there is no conspiracy; just a huge vital market, better than ever. No need to invest the equivalent of a car, to try or use one typeface like in the olden days.
Try walking into a car dealership and wanting a certain car, but with lesser specs and with a real discount. They will probably laught at you and will say "we will not remove the radio, and then do what with it"... You can custom-order certain cars (in Germany), if you are willing to wait and pay for it. For typefaces you got lots and lots of choice and practically no wait at all.
In Religion, in IT and in Design the "why" questions will often not give you very sattisfying answers. Or any answers. I just feel chatty today but there is not much of an answer: Just enjoy and learn about the differences:
The Garamond you mention is available as "open source" I believe, so this gives you possibly a good and not-expensive example to pull several different offers and compare not only what you get but also compare the different websites, the way they function, their customer services, efficiency in handling your account and keeping your purchases available for you. Like with cars, you do not only purchase a product (like a tin of cookies), you buy into a living system of product + vendor + maintenance (updates) + customer care + documentation (or not) + chances for updates or upgrades (or not)...
Normally on this site you should only post one question per item. Your question about kerning is rather different, especially since you mention a totally separate typeface for comparison. I propose you edit this question and make a new one about kerning. Please give an export or a screenshot of what you consider "very very bad kerning". It could be a technical problem, or it could be a difference of schools of style, but we do not know until you show how bad it is in your context.