It's probably not necessary and maybe not possible for it to be possible for one person to know and understand all of the laws for a society to be large, prosperous, fair and just. It probably is possible to have all the laws published on a government-run website that's free for all to access, indexed and cross-referenced.

Furthermore, it is probably possible for most reasonable people in such a society to know what fields of human endeavor are regulated under the law and to look up and understand the applicable regulations. Of course, some fields and their associated regulations are very technical, but it seems to be a reasonable goal that anyone with enough expertise to work in such a field, even as an amateur can also understand the associated laws.