Why are the approaches so different depending on the country?

In Switzerland, a liquid diet usually isn’t required before surgery. On the same day after surgery, a maximum of 0.5 liters of water is allowed. On the second day, patients can have water or unsweetened tea without limits. On the third and fourth days, cream soups are introduced, and by the fifth day, mashed potatoes and soft, white bread with a little butter and jam are permitted. One week after surgery, patients can eat soft-cooked pasta, rice, potatoes, and vegetables, as well as bread, lean, and soft-cooked meat. The focus is on consuming minimal sugar and fat.

And it works! No dumping syndrome, no nausea, no pain while eating (eat slowly/chew well).

Where are you from and what is your experience?