Why is there no uniform standard for the configuration of solar street lights?1

With the advancement of photovoltaic technology, the use of solar energy has become more and more widespread, and many rural street lights have also used solar energy. Solar street lights have been widely used in rural areas. However, the price of solar street lights on the market is uneven, mainly because there is no uniform standard for their configuration. Some configuration is high, naturally the price is high. Some configuration is low and the price is naturally low. So why is there no uniform standard for the configuration of solar street lights?