I don't think merchants prefer Afterpay, they tolerate it because it can drive extra income from people who otherwise can't get credit cards or have maxed out their cards. 6% is not paltry but rather significant in the face of ever increasing overheads.
If visa comes out with a cheaper alternative and markets it well to millennials then APT will have some competition with firepower.
APT Price at posting:
$27.00 Sentiment: Hold Disclosure: Held