It's not instant and it relies on a private company for settlement. Even though customers typically get this for "free", the institutions themselves are paying interac for these (so the account-holders are paying for this one way or another)

From what I can tell, e-transfers will continue using interac's network, so I'm not sure if this will benefit users at all. Depends if banks integrate a new user-facing money transfer option. I suspect it'll take years if not decades for banking institutions to roll this out to users, though they may use this behind the scenes for inter-institutional transfers without Interac.

Someone who's more knowledgeable about Canadian banking and payment processing, feel free to jump in here because I'd like to know more as well.

When I sell things on local used sites I started only accepting cash because e-transfer is so slow and led to situations of someone standing in my entryway while we wait to confirm the money went through.

Or giving up and saying "alright, I guess I'll trust you and hope the money comes soon"

Interactive etransfers are far from instant. My last company supported etransfer payments. On a good day they would take ~10s to process, 30s was decent, and single digit minutes were normal. Legitimate payments that got flagged by Interac's fraud detection rules were often subject to delays measured in hours, sometimes days.

Good enough for consumer to consumer use and some online use cases, but definitely not good enough for retail.