Most mobile wallets today default to an Electrum server for balance detection and transaction history.
I know it is fast, convenient, and is indeed standard these days.

But it comes with a well-known cost, privacy.
Requesting data to Electrum server of others leaks address clusters or txn patterns.
Obviously the ideal solution is RUN YOUR OWN NODE AND ELECTRUM SERVER,
but not everyone runs their own node, and even those who do sometimes have to deal with downtime or connectivity issues.
When the connection isn’t immediately available, this often leads to falling back to someone else’s Electrum server anyway.

What’s strange is that we already have a working alternative, CBF neutrino peers. Wallet like Zeus LN use CBF to detect relevant transactions without directly revealing wallet activity to external electrum server. Yes it uses more bandwidth and battery up front, but most users seem tolerating and treat it as sort of tradeoff for privacy, and there hasn’t been a collapse in ratings or constant complaints that it’s unusable because of how it fetches utxo balances.

QuestionQuestion

My question is why don’t major mobile wallets like BlueWallet or Nunchuk offer CBF as a native or even as a fallback or advanced mode?

Yes, CBF isn’t perfect, it is even slower, especially at first.
But Bitcoin was never optimized for speed at the expense of sovereignty. A wallet that never asks to external server “what’s my balance?” seems closer to Bitcoin’s original design goals than one that does no matter how fast it loads the balance.

If CBF works fine in wallets like ZEUS, then the problem probably isn’t technology.
What would be the reasons for this, from a wallet developer’s perspective?