I know that the prohibition against placing stumbling blocks before the blind has been understood to be a prohibition against misleading or causing people to sin, but the simple meaning of the text is to not put an actual physical stumbling block in front of a blind person.
All rules are written for a reason. Torah rules even more so. Many were written to separate Jews from other ancient Near Eastern peoples. Is this an example of one: did the Jews' neighbors literally place stumbling blocks before blind persons? Even if there's no external historical evidence of this, are there Talmudic references to these practices of non-Jews or pre-Jews (or G-d forbid, of Jews)?