I think we’re dealing in generalisations.

Sure police forces have been used at various times to protect capitalist interests, and to protect vanguardist dictators.

Just thinking about my (indirect) interactions with police here in Western Australia in the last few decades.

• A friend of mine was charged with driving while intoxicated.
• They showed up to my neighbours house to resolve a domestic dispute.
• They charged an acquaintance with theft.
• I reported a theft at my home which they investigated.

I guess theft could be related to “protecting capitalist interests” but we’re not talking about the theft of someone’s million dollar yacht or gold bullion or something. My acquaintance stole some tools from a construction site, and some nice shoes were stolen from my front verandah.

IMO all of these things are just social harmony type things.