共享廠商佔用公共投入的最適決策及政府政策規劃

隨著不同社會環境的演進，經濟活動亦跟著改變，為了有效運用資源，使其效益達到最大，共享經濟這種創新活動自然而生。共享廠商透過第三方平台把共享設備資訊傳達給承租方，讓共享經濟的類型逐漸的變得具有多樣性。其中使用公共投入如土地的無樁式共享設備，卻很容易製造經濟環境髒亂，產生對社會不利的負的外部性。本文主要探討免費使用公共投入的共享寡占廠商之最適要素決策行為，透過不確定經濟模型的嚴謹推導，分析政府實施罰金、課稅不同政策對共享廠商利潤期望效用極大化的決策影響，同時也考慮共享廠商具有自主管理行為時，在政府實施罰金及課稅等政策的影響。最後，再分析政府相關政策的社會規劃問題。本文發現，若寡占市場上相同的共享廠商雇用無樁式共享設備，以提供給消費者共享交通服務。當政府採取罰金政策，在極大的期望利潤效用下，無論風險趨避的共享廠商是否具有自主管理能力，都不會影響共享廠商的最適要素決策及最適產量，其原因為罰金是加法的線型函數，但最適利潤之期望效用水準卻會下降。而當政府採取課稅政策，無論共享廠商是否具有自主管理能力，則共享廠商的最適雇用勞力和資本，以及最適共享服務產量將會減少，但期望利潤效用水準仍會下降。在分析政府相關政策的社會規劃問題時，我們發現若共享服務市場為寡占型態，不論所有相同的共享廠商有無共享設備的自主管理能力，當共享廠商家數增加使寡占市場獨占力下降，此市場結構改變將會增加同質寡占市場上所發生的外部成本，但不影響政府決定的最適罰金或課稅政策，而會提高最適社會福利水準。

關鍵字

共享經濟；共享廠商；共享單車；公共投入

並列摘要

With the development of social environment, economic activities have changed. In order to use resources efficiently and maximize people’s benefits, innovative activities come very naturally such as the sharing economy. Sharing firms can transmit the information of sharing equipment to tenants by the third-party platforms, so the type of sharing economy has gradually varied. Among them, the non-pile sharing equipment using public input such as land bring about a dirty economic environment and produce negative externalities more frequently. This thesis discusses the optimal factor decisions of the sharing firm that using public input for free. Through rigorous derivations of uncertain economic models, we analyze the impacts of different government policies of fine or tax on the sharing firm’s optimal decision to maximize expected utility of profit. Also, with spontaneous management behavior of the sharing firm, the impacts of fine and tax policies have been analyzed. Finally, we research the social planning problem of relevant government policies in detail. We find that, if the identical sharing firm on the oligopoly market hire non-pile sharing equipment to produce sharing transportation service for consumers and the government implements a fine policy, regardless of whether the risk-averse sharing firm has self-management behavior, the fine policy will not affect the optimal factors and the optimal output of the sharing firm maximizing expected profit utility. The reason is that the amount of fine is a linear part of the profit function. However, the level of expected utility of the firm’s optimal profit decreases. When the government implements a tax policy, regardless of whether the sharing firm has self-management behavior, the optimal labor and capital hired by the sharing firm and the optimal output will decrease, however, the expected utility of the optimal profit still decreases. By analyzing the social planning problem of relevant government policies, we found that if the sharing service industry is oligopoly market, regardless of whether the sharing firm has self-management behavior, a much larger number of identical sharing firms or a market structure with less monopoly power will increase the external cost. As a result, the increase in the number of sharing firms will not affect the optimal fine or tax policies determined by the government, but will increase the optimal social welfare.