Illegal Africans, Pakistanis or Vietnamese working in China are 'Pariah'.

Western ones aren't. Its because Westerners are taking a reduction in life quality to bring value to China.

Mexicans (by and large) are taking an undeserved upgrade in quality of life in exchange for lesser skills and ultimately a net loss to America.

Believe this: There are 'undocumented' Chinese coding wizards in Silicon Valley and they are not 'Pariahs' but whatever you'd think the opposite would be and they will smooth out any issues (if anyone ever bothered finding a problem in the first place). A company boss will quickly send a legal letter taking full blame for the 'visa mistake' and agree to pay the fine for the worker and then pay to sort out the workers next year or problems ASAP.

But illegal aliens taking over LA neighborhoods are about as popular as Africans taking over Guangzhou districts are in China. Difference being very few Blacks in Guangzhou are taking welfare, social services and prison space in Guangzhou.