> Where are you that this is true? This is directly opposite of my experience. I genuinely can't remember the last time a Prime/2-day shipment was delayed.

It happens all the time where I live. It's also not uncommon for my Prime packages to get totally lost by Amazon Logistics (I've never had that happen with another courier). At least now they automatically cancel those orders, I previously used to have to call them to tell them what to do when they lost my packages.