Your argument ignores the value of diversity within a business. A diverse workforce offers much more variety in how to progress the company. Peoples of similar traits and backgrounds tend to have similar ideas and methods. More diversity can increase problem solving, customer relations, and ingenuity by forcing all parties to see things from different perspectives.
The US has a long history of employers refusing to hire minorities/paying the “othered” less. We are not so far removed from these practices to reliably function without laws and regulations ensuring businesses not fall back to old habits. Slavery in the US ended around 150 years ago. The Jim Crow laws, officially, almost 60 years ago. Sundown towns were still around, though not as common, 45 years ago.
Signing is a verification of having received the citation. It is an important safeguard. An individual cannot (as easily) claim to not know about the citation when their signature is on it. Police cannot create citations after the fact because of the required signature.
However, there are a lot of people who misunderstand the purpose of signing. People often think signing is an admission of guilt, or otherwise agreeing to the charge. If I had to guess, Vu thought something similar. I’m sure the language barrier did not help.
That cop still outrageously overreacted and should face charges and termination… Not that it will happen, but one can dream.