How are they not comparable?

Debian's scale for package distribution is tiny and explicitly curated by maintainers. Everything funnels through Debian. The goals are completely different. Debian packages what's necessary for an OS, npm packages everything needed for any projects arbitrarily. Auditing scales to one of those, not the other.

The quantity of packages that exist at 162150 seems to say to me that there's a great many more than what are "necessary" for the operating system to exist.

sudo apt-cache stats

Total package names: 162150 (5189 k) Total package structures: 145852 (6417 k) Normal packages: 69505 Pure virtual packages: 1169 Single virtual packages: 64848 Mixed virtual packages: 355 Missing: 9975 Total distinct source versions: 71172 (1708 k) Total distinct versions: 71172 (6334 k) Total distinct descriptions: 139719 (3353 k) Total dependencies: 435057/121405 (10.6 M) Total ver/file relations: 73378 (1174 k) Total Desc/File relations: 142692 (2283 k) Total Provides mappings: 70533 (1693 k) Total globbed strings: 268430 (6560 k) Total slack space: 77.3 k Total space accounted for: 47.0 M Total buckets in PkgHashTable: 196613 Unused: 93545 Used: 103068 Utilization: 52.4218% Average entries: 1.4151 Longest: 19 Shortest: 1 Total buckets in GrpHashTable: 196613 Unused: 86025 Used: 110588 Utilization: 56.2465% Average entries: 1.46625 Longest: 7 Shortest: 1

162k vs millions. That's not even getting into package update velocity, authorship, the totally divergent goals, etc. I just think it's utterly pointless to compare.