Answer:
DNA polymerases are involved in the production of new DNA molecules while RNA polymerases are involved the transcription of DNA to mRNA.
Error correction is not necessary in RNA polymerase as compared to DNA polymerase because
1. The production of mRNA from DNA is for a period of time, that is, it is finite and when it is converted to proteins, it can be degraded. But the DNA replication is from generation to generation as it is inherited
2. The process of transcription is so fast. Thus, just few number of transcripts will have errors compared to the number produced.