These are taken directly from the physical discs. While the resolution is technically 480p, a high-bitrate MKV file will often look better than a "720p" file that has been over-compressed.
When the show was available on streaming platforms like Netflix, the digital files provided a significantly cleaner image than the original 2008 TV broadcasts. Many "720p" torrents are rips from these digital platforms (Web-Rips). Power Rangers Jungle Fury 720p Torrent
Hasbro has been incredibly generous with the back catalog. Many seasons, including Jungle Fury , are uploaded in their highest possible digital quality for free. These are taken directly from the physical discs
While torrents are a common go-to for archival purposes, there are easier (and legal) ways to get high-quality Jungle Fury episodes: Many "720p" torrents are rips from these digital
This is a modern compression standard. An x265 encode will give you 720p quality at a much smaller file size without losing detail.