Lack of elbows?

[montageUK]

I have bought a house in Italy that has a septic tank. Clearly it has worked fine for many years but I was surprised to see a broken inspection cover that revealed a complete lack of elbows (see pic). I'm not a professional plumber but wouldn't this just cause waste to back up in the chamber and cause a blockage? Is this normal or should I consider adding elbows with appropriate rodding facilities?

Many thanks
Tony