為什麼理論與實際差距很遠?

Business theories are concepts or business models which do not consider all the real situations or simply assume all or most of elements are constant. In the real world, there are any factors that affecting the business operation and result.

For example, the price of property, economists assume that property value is relative to basic elements (eg, location, usage and size), economics elements (inflation, GDP, purchasing power and completition) and political factor (stablility, government city plan) etc. However, property value also influence by personal preference, actual space size, target of profit sellers, envoirment around, view/direction and historial price, etc. Therefore, properties on the same building with same sizes facing different directions are valued at the same price by bank but priced differently in the real market.

2009-07-15 13:50:45 補充：
For your second question, big company ususally enjoy a lot of advantages, like large scale of production, long credit period, stronger bargain power, large market share, etc. Oppositely, SME has more limitation and restriction when they are trading with big company.