Why were the older punishments, such as the stocks, not used so much after 1750?

From 1750, the older "shaming" punishments , like the stocks and the pillory,fell out of use. So did Whipping. Fewer people were hanged in public as people thout that hanging was too barbaric. For most of the 18th century and the first half of the 19th century, transportation was a common punishment. At first, people convicted of crimes were sent to America, then after 1776 {when America declared independence} they were sent to Australia. At the time, little was known about Australia and it was thought that the fear if being unknown and being sent away so far away would prevent others from committing crimes.