Perhaps because it allows "them" to catch whoever they feel like, and claim "oh, the computer said they were a criminal".
I'm astounded anybody who lives in a country where police can and do get away with shooting and killing people for faulty taillights - could possibly think this is a good idea...
Resisting arrest is a typical workaround for that. The antidote is, "well why were you arresting him?" This dilutes the antidote with, "the computer said he was a criminal."
Also, we make way too many things illegal in the US and the punishments are often harsh for a country founded on "freedom." I wish more people would shed this archaic delusion.
Ask anyone from any sort of minority community how often their members get charged with resisting arrest vs how often they _actually_ resist arrest. Even allowing for self reporting always making the comparison skewed I suspect most non-minority people won't even believe the difference.
Over here (Australia) they call it "the trifecta of charges" - offensive language, resist arrest, assault a police officer - and it's well known to be used as "Arrest as a method of oppression".
These regularly get thrown out by victims capable of fighting them in court (eg: https://www.smh.com.au/national/nsw/arrest-of-student-for-of... ) - but they're overwhelmingly used against groups who're least likely to be able to do that: "Indigenous Australians account for 15 times as many offensive language offences as would be expected for their population." http://www5.austlii.edu.au/au/journals/AltLawJl/2004/53.html That's not because white folk are any less likely to tell a cop to fuck off, it's because there's systemic racism built into the police force here - they "know_ they'll get away with "the trifecta" against "people who look a certain way".
Resisting arrest is pretty vague. If you say, "hey, wait a minute, let me explain," while they are turning you around to cuff you, that can be considered resisting. Really it doesn't have to be anything, they can just put that on the list of charges.
The courts in the United States regard resisting arrest as a separate charge or crime in addition to other alleged crimes committed by the arrested person. It is possible to be charged, tried and convicted on this charge alone, without any underlying cause for the original decision to arrest or even if the original arrest was clearly illegal.
That last sentence is the kicker. If a cop makes an illegal arrest and you resist non-violently, you get charged for it. Think about that for a minute. That alone gives any officer the ability to arrest you for anything they want, then claim resisting arrest and you now have a prosecutable charge, even when the arrest was clearly illegal. This is the case, do we really even have rights in the US, or is it an illusion?
I'm astounded anybody who lives in a country where police can and do get away with shooting and killing people for faulty taillights - could possibly think this is a good idea...