The police had every reason to stop you: you failed to signal a turn (or you did not come to a complete stop at a stop sign, or you were speeding, or any number of other violations).
The real problem here is that there are far too many laws, which has led to a situation where the police can find a "legitimate" reason to arrest/search anyone. There is also the matter of victimless crimes (like possession of certain drugs), which can turn minor infractions like speeding into 20-year prison sentences. The massive increase in police budgets and power over the past few decades added fuel to the fire, but we were in trouble from the beginning.
The real problem here is that there are far too many laws, which has led to a situation where the police can find a "legitimate" reason to arrest/search anyone. There is also the matter of victimless crimes (like possession of certain drugs), which can turn minor infractions like speeding into 20-year prison sentences. The massive increase in police budgets and power over the past few decades added fuel to the fire, but we were in trouble from the beginning.