Why is it difficult to retrieve a body from Mount Everest?

Experts said 8-10 Sherpas are needed to retrieve a body from Mount Everest and conventional stretchers cannot be used due to narrow passages. The operation can cost up to ₹1 crore, while rescuers risk danger as only one-third of oxygen we breathe at sea level is available beyond 8,000 metres. The terrain is challenging, with steep and slippery rock faces.