Why do the towns lawmakers feel that they were merciful to Hester concerning her punishment?

The town's lawmakers may feel they were merciful to Hester by not sentencing her to a harsher punishment such as death or imprisonment. Despite publicly shaming her with the scarlet letter, they may believe that allowing her to live and raise her child was an act of leniency. The laws and social norms of the time may have dictated that a punishment like public humiliation was considered merciful compared to more severe consequences.