My understanding is a 1:1 peg is optional. And there is no mention of pegging the block rewards which would also be required to maintain a 1:1 pegged relationship.
1:1 is optional indeed but then the sidechain is no more a BTC application specific chain but a sidecoin, the younger brother of the altcoin.
Pegging the block reward? I think this explains your misunderstanding.
A 1:1 sidechain is not created with any unit in it. There are no block reward issued coins on a 1:1 sidechain, only coins that are locked by their owners in that chain.
There's no misunderstanding, there are valid applications for SC (I still think OT is a more practical solution for those trust free situations) I realize there will be all kinds of SC, but in principal thay are off blockchain ledgers with a mechanical link to Bitcoin - some with tokens some without some with MM some without. But ones with tokens that require MM will have tx rewards and they will be writt to a separate ledger and they'll need to reward miners, that may not even be written in blocks, but the economic incentive will be the same. You can't say how SC will be create or used so I think it's dishonest to say there won't be any 1:1 pegs that have odd rules.