I've run into this problem several times, and the only thing that has ever worked for me to reliably reset the SVG viewbox to precisely 0, 0 when exporting from Illustrator is to create a new blank document and copy and paste the artwork into it.
The top left corner of this untouched default artboard will export as point 0, 0 of the view box. Use smart guides (
cmd-u) or the
align window set to
Align to Artboard if you need your artwork to start at exactly 0, 0.
You can safely resize the artboard from the bottom right corner, but things start to go wrong if you move the top left corner. Moving the artboards' top left corner or importing SVG files to AI seems to cause some kind of weird internal disconnect between the rulers, artboards and some sort of invisible secret viewbox origin point known only to Illustrator.
AFAICT, as with most things to do with web or emerging technology, Adobe's approach to SVG has been to throw something crudely together so they can boast about it in a press release, then leave it buggy, unfinished and unloved, pretending it doesn't exist and carrying on like it's 1998.