Robots need to be programmed. Even the simplest task takes a lot of effort to program and then even more to debug. During that time the robot produces a lot of faulty product that needs to be scrapped.

Large companies can afford the programming costs because the amortise the development cost over a large number of units.

Small businesses generally do not have the resources to market, distribute and sell large quantities of product. Thus you need a lot of capital to play in this game.