We just laid a new slab for a doublewide that’s moving in. The local township inspector is hyperactive and strongly suggests he’s going to want a retaining wall be put in. Here’s a photo of the site:
Do you think a retaining wall is necessary here, or should I push back on this?
This is coming from the peanut gallery, but if there is landslide or mudslide risk then you should put one in.
How much higher does the hill go above the pad? If your in high rain area you might want a french drain as well as wall.
Do not mess with inspectors on a minor issue like this. If you get heavy rains it could wash down. Easier to do what they want this time to build a positive relationship with inspector.
I would tile it for sure. Not just heavy rains you have to worry about. Depending if you get freeze and thaw like is it will be on going. Retaining walls are only as good as the person building them. Consult a pro.
Noel
I would definitely heed the advice of the posts here as well as the inspector. As mentioned, in addition to prevention of mudslide, you should have a method to divert all water away from that house, or in this case around that house from the slope.
As a homeowner, I would not like to have my home on that lot. 
We have a large park in Missouri and I sat thru the installer class. It was a great experience and very educational. The state takes the installations very seriously.
In the class their were ample examples of installers who tried to do their own and the outcome was bad.
The inspector is your licensed expert. They are not trying to add unnecessary work and expense. I would just go with all the things the inspector is asking you to do and you can verify this with your licensed Installer or the inspector’s manager as well.
All the best!