Regulations are ever changing because regulators want the market to be a certain way and companies will look to innovate and sometimes this is in a way the regu

Regulations are ever changing because regulators want the market to be a certain way and companies will look to innovate and sometimes this is in a way the regulator doesn't believe is in people's best interests. If you look at MiFID 2 that came into effect at the start of this year, it cost financial companies significant amounts to comply. Many of these companies would prefer it didn't exist. Others have identified opportunities from the changes that they can use (Dark pools being less prevalent and the rise of Systematic Internalisers). Its complex because there are lots of moving parts and regulators want to keep the market in check without having undesired consequences.