"The NTSB has a long history of concerns about the safety of various revenue passenger-carrying operations, including sightseeing flights conducted in hot air balloons, helicopters, and other aircraft and parachute jump flights. These operations are not subject to the same maintenance, airworthiness, and operational requirements as other commercial flight operations."
Source: From an NTSB statement explaining the rationale for an upcoming public board meeting March 23, 2021, 0930 (EST), to consider a draft report on recommendations for the implementation of stricter regulatory requirements for some types of revenue passenger-carrying general aviation operations.