The author also gives a rationale for choosing the EUPL (EUROPEAN UNION PUBLIC LICENCE) here: https://www.arp242.net/license.html.
ksec posted this link: https://github.com/zgoat/goatcounter, but, at the time of writing, my comment is higher...
It provides rationale for why GoatCounter exists and comments about _why not_ other solutions like Fathom, Open Web Analytics, KISSS, Ackee, Countly, Analysing log files, Google Analytics, statcounter, Simple Analytics, getinsights.io, statcounter.com. plausible.io/.
> Have a “strong” copyleft, including the so-called “network protection”, which mandates that people submit changes even if they operate the code as a service (rather than sending people binaries).
However the EUPL allows you redistribute under other "compatible" licenses most of which don't provide that "network protection". Effectively, the EUPL is only as strong as the weakest "compatible" license listed in the appendix.
 These "compatible" licenses wouldn't otherwise be compatible, except that the EUPL explicitly allows re-licensing to them instead.
ksec's link is: https://github.com/zgoat/goatcounter/blob/master/docs/ration...
BTW I love your website's design!