How come can WinSCP or FileZilla not be listed in HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\*).DisplayName
WinSCP installer is a 32-bit application (so it can be used on both 32-bit and 64-bit systems).
As such, it writes to 32-bit registry path on 64-bit systems:
HKLM\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Uninstall
I assume the same for FileZilla.