First off, there are some fields where scientists can write their own ticket. Certain medical areas where an MD as well as a microbiological PhD is required, those guys just don't hardly exist... I've heard of relatively insane levels of pay for them.

Then if you do get a good research position somewhere, you get your base pay and all but a lot of scientists reach out for grants and they can pay themselves from them, padding their base. If you can get one of those cherry positions, it's potentially way nicer than what most engineers make. If you work on things with industrial applications you can get royalties and such, all while working at a university. Seems a number of these places have like real pension type retirement programs as well.

The haves in science are doing great, the vast majority are have-nots though and they live near poverty in a lot of positions. It's my opinion looking in (my wife is a scientist) is that there are 2 main problems: 1) Little understanding and appreciation for real science, it's thankless, there are tons of failures to usually make incremental progress, the level of meticulousness is something else.. and 2) They've got their own culture running it now and there is a history of paying dues and lot's of unwritten traditions about how you can grow and evolve a career. Post-docs don't get paid much, that's how it is, even if a lab can afford it, post-docs don't often get jobs where they post-doc, even if they're experts on the lab's area of work because that's just not how its done. It's kind of like how MDs are stereotypically just ground up by working insane shifts at the at their residency because that's what the doctors before them had to do, almost like hazing..