I've long been aware of their $6k warranty of title. Only someone from Hwaci could give an accurate count of purchasers (they only say "Most people use SQLite without any kind of license or support"), but I would bet that not even half of the developer-users and distributors of sqlite directly (let alone those of sqlite indirectly through other products or libraries that bring it in or embed it, which they are under no obligation to disclose) in countries like Germany have actually purchased one. I doubt it's even a significant money-maker for them given their range of available things for purchase (https://www.sqlite.org/prosupport.html). It's not a problem in practice, it's exceedingly unlikely to ever become a problem, but sure, a lawyer can find a vulnerability in everything, even with GPL (which is part of why some US companies have a blanket "no GPL" policy).

I'm glad they offer the warranty of title and take money from companies with edgy lawyers, though. $6k is small as legal fees go. It's in general a lazy monetization strategy I broadly agree with and I've been hoping GitHub under MS's stewardship would help spearhead a simple way for people/companies to buy secondary-licensed copies of software without having to contact the author about it. (I think I got the idea from Zed Shaw around the time MS bought GH.) Like, a lot of software out there isn't a mess of contributors like the linux kernel each holding their own copyright, and thus much of it can be relicensed or dual-licensed without fuss. When people license something under the AGPL or even public domain if they're copying sqlite, sometimes they include something in the readme about being open to selling an alternatively licensed version/warranty of title to companies who have some issue. But even if they don't explicitly mention it, companies can still fruitfully contact such authors and make a deal. This happens all the time on twitter of all places, with journalists asking some user (who may not even be legally identifiable from just their handle) to re-use their apparently original photo or video. Sometimes the user just gives permission, sometimes they demand "pay me", sometimes a payment is actually made. Douglas Crockford has given permission (not sure if he got any money out of it) at least to IBM to use his software for evil, again showing his infamous clause is only a problem for people who decide to make it one.

Basically, I'd rather not tell people how they can license (or not license, as per public domain declarations) their code, and while it's fine to be aware of usability tradeoffs and it's fine to know that some edgy companies or users in other countries might write you off for your choice, it's important not to overstate the actual risks involved relative to the base rate risks already out there (like patent trolls) and it's important to recognize that solving the problems in ways even the edgiest of lawyers can be mostly happy with is often possible. Having blanket policies instead of pursuing those solutions is also a choice people are free to make.

(Writing this comment led me to https://web.archive.org/web/20120510151444/http://methodlogi... which is interesting in that it could suggest how further knowledge of tradeoffs and future pushback in the beginning may have led sqlite to be put under a license, however I don't suppose anything legally stops the authors agreeing to relicense in a new version since they retain a clean title, it's just there's no compelling practical reason like seeking more contributors.)