I don't exactly blame the business for requesting proof... Im sure they're not calling you specifically a liar, but scams are just as common from buyers as they are from sellers, so they're just trying to protect themselves.
Pretty much this.
Asking for proof is NOT an attack or judgement on you. Its completely normal. You pretty much always need to provide proof if you're claiming a package/item was damaged during shipping, is defective, the wrong thing was sent, etc. The vast majority of places require this.
Its annoying, sure, but its not malicious or mean.