Yes, charging for a missed service when the truck cannot reach the unit is normal in portable toilet rentals. Most rental contracts put access on you, the customer. That means a working gate code, an unlocked gate during the service window, and a clear path for the vacuum truck.
I run small residential sites in Columbus and I have been hit with this exact situation. Drivers will not climb a locked gate or sit and wait. If they roll up, cannot get in, and leave, you still ate a service stop. The waste tank does not get pumped either, so the next visit can get messy if the unit is already heavy.
What I do now: put the gate code in the order notes and text it the morning of service. If the gate is keypad only and flaky, I leave it unlocked for the service window or hang a temporary lock box. I also ask for a call or text if they bounce so I can open it before they leave the area. Confirm the service day and rough arrival window when you book so you are not guessing.
A standard portable toilet on gravel fifty feet in is fine for access once the truck is through the gate. The issue is the gate, not the placement. Read the missed service or dry-run line in your rental agreement so you know what they can bill. For what a service visit usually covers, see servicing.
