In order to be charged with wnic/delivery of a controlled substance... Do they need to have proof of me selling drugs if I didn't have over the amount

My friend got pulled over the cops said cuz the car was stolen but after they drew guns on us and got us out the car they found like less than a gram of fetanyl and less than a gram of heroin and no proof of them seeing him selling drugs to anyone arrested not for possession but for the charge wnic/delivery of a controlled substance and then they searched his house didn't say anything about a search warrant and only found three 9mm clips and 2 or 3 45 caliber clips, notes, addresses, phone records, three scales... Like I feel they sent an informant to him or someone snitched cuz why they said they pulled us over was cuz his car was stolen it wasn't for drugs.. They didn't even say in his charge that he's in jail for that they found heroin too or coacaine like he had all three but they were all less than a gram each.. Like I feel for them to charge someone for delivery they should have witnessed the sale or a snitch. The search warrant says drug trafficking that they left at his house