How hard is to cheat or bribe to get the other requirements, too (recommendation letter, charity, etc.)? I come from a country where grades are the main variab

How hard is to cheat or bribe to get the other requirements, too (recommendation letter, charity, etc.)? I come from a country where grades are the main variable, so I'd like to have a view on how these additional requirements make the whole process more robust. Is it just for a quantitative reason (cheating on N > 1 requirements is more difficult than cheating on 1) or are they necessary to correctly identify good candidates?