the reason why people are refused is no one knows what the criteria is to get a visa, because really is no set criteria, most of it is at the discretion of the case worker, so someone might be granted a visa and another case worker might refuse them, so it is unfair.
if the gov set and published what exactly was needed say for a visit visa (£xxx per week to fund your stay) and end theabout they dont believe you will return before your visa expires, why did the gov scrap the planned deposit system they had planned, you dont go back you lose your deposit and ban them for life.