lossless isn't meaningless. Re-encoding introduces a lot of artifacts. Imagine your comment in 2001 when someone stored their movies in mjpeg or whatever. The moved to MP4, than the h264 than perhaps to HEVC. You realize how shit that movie would look after all those re-encode cycles?
That's exactly what im talking about.
Re-Containerizing MPEG-TS as-is to something like mkv, vs. Transcoding is exactly what I'm talking about here.
There are currently not any meaningful ways known to me, to even make MPEG2 files significantly smaller in way more modern and advanced codecs without loosing perceived quality even at the same bitrate.
Not even talking about interlacing issues here.
So for anything MPEG2 and newer lossless reencoding seems quite a futile excersise to me from my personal experience.
If there is a promising way I'm all here for it, but this sadly doesnt look like it.