There's 100mg available in EU in several places, in addition to already mentioned, then also e.g. pink-mule.com, mixnmatcheliquids.com., toscanamall.com and e-cigshop.eu etc.
The no 100mg in EU notion, comes from the UK which have a poison-act limiting the selling of nic over 74mg without a specific poison-license in place. Maybe that posion-act is now replaced by REACH in UK I dunno. Someone on reddit stated that it's an universal EU law as included in REACH, but I haven't seen it posted where that's precisely stated, but don't know personally. Most stating 72mg max, are referring to the UK possibly outdated poison-act, which isn't max 72 but 74mg.