Scanning the star was especially painful if you were exploring in an Anaconda or some other large ship with an atrocious Supercruise turn rate. A lot of cherry-pickers and credit-seekers flying those ships never bothered scanning the star as it took up too much precious time turning in towrds the star, wait for scan, then turning back away from the star again, all for very little credit reward.
It does mean that there's an awful lot of in-game and EDSM systems that are only partially explored, where the ELW (for example) is scanned but the star itself is not.