Mainly because US investors are lazy investors:

1. The security is in USD (no change required)
2. The security trades at normal US trading hours (not with time delay due to time differential btw the US and the country of origin of the company)
3. It is treated as a local security in your tax declaration hence easier to declare to taxes from an individual investor’s perspective

https://en.m.wikipedia.org/wiki/American_depositary_receipt

Liquidity would be my guess.

But Wikipedia has a decent article on Cross Listed companies

Liquidity