Comment by Canada

All of the system group names that own resources for specific applications have been underscore prefixed for years... like

  ...
  _bgpd:*:75:
  _tcpdump:*:76:
  _dhcp:*:77:
  _mopd:*:78:
  _tftpd:*:79:
  _rbootd:*:80:
  _ppp:*:82:
  _ntp:*:83:
  _ftp:*:84:
  _ospfd:*:85:
  _hostapd:*:86:
  ...

but not the general ones like wheel, sys, daemon, tty, nobody, etc.