Why can't I type in my own tip, buy or licensing address?

To protect creators. Because anyone could register someone else's Ordinal by its public TXID, allowing free-typed payment addresses would let a stranger redirect your tips and sales to themselves. So BSV Search only ever uses payment addresses that are inscribed in the Ordinal itself, on-chain. If an Ordinal has no inscribed payment address for an offering, that offering simply isn't shown — money can only ever reach an address the creator committed to on-chain.