Passenger-Side Mirror

Typically, passenger side mirrors on cars have a different magnification than the driver's side mirror. This is done to provide a wider field of view on the passenger side, which helps to reduce blind spots and improve visibility for the driver. This improves safety, not reduce it.

If you're coming from an older style of mirror then there is some learning to be done and time spent getting used to it. Mirrors on every car I've ever driven in the US in the past 25 years (I'm from the UK) have always had printed on the bottom something to the effect of "Caution: Vehicles appear further away than they really are", or something along those lines, to remind drivers of this.

The passenger side mirror is often more convex (wide-angle) than the driver's, to compensate for it being further away from the driver than the driver's mirror. The further you are away from a mirror, the less the field of view so the mirror compensates for this.

The different magnifications of the two mirrors help to optimise the overall visibility and safety of the vehicle.

On some vehicles and in some countries, the driver's side mirror often has a variable and increasing convex curve is it gets towards the outside edge, providing very distorted views of vehicles in that area of the mirror, but it also allows cars in your "blind spot" to be somewhat visible, which again improve safety as being able to seem them a bit is better than not at all.

So with the mirrors, it's more a matter of getting used to them and understanding them, rather than them being unsafe.

Give it a while, but if it continues to be an issue then you can get different third-party glass for them, but be mindful of things like the heaters in them if your car has them. You can also get mirrors that stick or extend them, but these can be equally annoying.

The rear visibility is generally worse as cars become more aerodynamic and/or longer, purely because the field of view narrows as both of these increase. There's no great solution to this, short of using extended side mirrors, adding an always-on rear view camera (you can get ones that turn your main mirror into a screen), or swapping vehicle shape.

 

Not a problem for me, just as @The Professor says, it is a convex glass to give an improved field of view.

I don't have any issue looking out the back at all, in fact I find the rear visibility far better then a Model 3 I drove a while back.

 

I don’t remember exactly which car I bought that first had these mirrors, but I remember a new 1979 Chevy Caprice Estate wagon that had them! So you would be coming from a pretty old vehicle here in the states to be experiencing them for the first time!
As far as rear visibility, the Prius pretty much beats any car I’ve ever had, except for the station wagon and an Austin Healey convertible!