If you apply your same line of thinking to a physical store then why does any company have more staff than the cashier? The point is that a company consists of way more than just what you interact with directly.

You need staff to clean, staff to provide support for other staff, whether that's catering, technical, or anything else. You need staff to ensure that your operations are not violating any local or national laws. You need to break the company up into smaller units in order to be manageable and you need management staff for those units. The list goes on and scales up as the size of the company grows - especially so when it's an internationally operating company.

It is, in the same way that light speed is the same for all observers. For example you travelling at the speed of light and turning on a flashlight results in the light emitted from the flash light moving forwards at lightspeed relative to you and we know that you can't go 2x the speed of light which is what would be happening from a 3rd perspective.

So the only way to reconcile this impossibility and maintain causality throughout the system, since nothing can go faster than light relative to any observer, is with time dilation.

The problem is our daily experience of how time and space operate is actually misleading. This makes it really unintuitive to conceptualise what's actually going on.

It turns out that time and space are the same thing which is called spacetime. Everything moves through this spacetime at the speed of light. There actually isn't any variation in speed of anything through spacetime. The only difference between anything is how much of their lightspeed through spacetime is specifically directed at moving through space and how much is directed at moving through time.

In order to move faster through space, you must deduct speed away from time because you have to maintain lightspeed through spacetime. This is also why you can't go faster than light. Firstly, you're already travelling at light speed through spacetime. Secondly, once you angle all of your light speed through spacetime so it's pointed at space then you have 0 angled at time and so you have no more speed to borrow from time to assign towards speed through space since you must always maintain lightspeed through spacetime.

In any given locality there are fundamental laws like not being able to travel faster than lightspeed and this also applies to the passing of time. It will always pass at one second per second for any local observer. Another law is that events between these different localities ultimately must be causally linked. The only way for events from one to impact the other and retain that causal relationship is if you introduce the concept of time dilation.

The experience of time is always the same for any local observer. Meaning that no matter where you are you will measure time passing at a rate of exactly one second per second. This means that it makes no sense to state that time is experienced differently because it is always experienced the same for any local observer and they're the only one who can have the experience of time at that specific locality. The only time there becomes a discrepancy is when time in one locality is measured relative to something else where there is a difference in either speed or gravity.

It's basically a measurement discrepancy rather than an experiential discrepancy.