I don't know anything about FastPass... so if something is for example Tier 1, does that mean there is no line for non Fast Pass users? It's strictly FastPass only? None of this was an issue 12 yrs ago.
Learn about Disney FastPass+ service and how it works at Walt Disney World Resort in Florida.
Tier 1 does not mean there is no standby line.
In Epcot, Hollywood Studios, and Animal Kingdom there are tier 1 and tier 2 FP+ selections.
The absolute headliners are tier 1 and the rest are tier 2.
You select 1 tier 1 and 2 tier 2 to book ahead of time if you'd like.
After you use them you can book another of either tier one at a time.
Use and repeat.
In Magic Kingdom there are enough attractions overall that the tiers are not needed.
Feel free to stand in the regular standby line for any of the attractions.
Its somewhat similar to other amusement parks that have a special pass you purchase at a hefty price to "skip the lines". That does not mean there is not a regular line for those rides.
Nice thing about Disney World is for now its at no additional fee and you can pre book 3 per each day on your ticket.
Disney uses the tier structure to restrict the types of rides that guest can select with the Fastpass+ system.
Example: when the Frozen Even After ride opened, everyone new it would be very popular. It was new so it had built up excitement for many guests, all the social media bloggers wanted the footage to get their clicks, kids love Frozen and also it was one of a few 'little kid' rides in Epcot.
Given all that demand, Disney added FEA to the tier 1 structure at Epcot. Guests are allowed one Tier 1 Fastpass selection to be pre-booked for the day. Guests had to choose between FEA, Soarin and Test Track for their Tier 1 booking.
If you wanted FEA, you couldn't pre-book Soarin or Test Track. You had to hope that you would find a Fastpass later in the day or stand in the standby which operated as normal.