Total Index is practically identical to S&P500 because Total Index is also market cap weighted.
The market caps of those US companies is huge because they do business across the world.
Even total market indices are not truly diversified though. For example the HSBC FTSE All World Index (which I do hold some of) still has a 58% US concentration and 27% in technology sectors (14% software services + 13% technology). For something marketed as global, there's still a massive concentration in the US and technology sectors
But then they wouldn’t have felt smarter than everyone else.