Under-developed idea

If you really wanted to compete with Venmo / CashApp / Zelle in the US with @base and USDC.

1. Allow any wallet or payments app (e.g. @daimo) to opt-in to the program

2. Require a reasonable proof-of-humanity / KYC attestation, e.g. Coinbase Verify coinbase.com/onchain-verify

3. Any time you pay someone new you get a $1 trading fee credit on Coinbase.com. If you refer someone to Base for payments (and they use your referral link for the attestation) you get $0.10 for each new connection made for referrals. The wallet or payment app gets $0.01.

4. Periodically disqualify any clear sybil rings.

Why does this work?
Similar to Zora rewards, you're incentivizing people overcome the friction for getting set up. You give wallets and payment apps (which don't have a great monetization path beyond swaps) incentive to push Base / USDC as payment option. 

You could also do this with DAI and a more decentralized stack, but harder to coordinate.