We also use contracting services for things like janitors here. The startup I used to work for didn't need dedicated cleaners, we needed maybe 1/4th of a dedicated cleaner. So we had an external service that paid to have someone come in and take care of all the things. But they in turn worked for a company that ensured they had all these things. So the costs were passed onto us, but only a fraction of it.

As for pensions it depends a lot on the specifics of the company. There are state run pensions here in the NL. Additionally you have some that unions, or the government have negotiated industry wide. So if you are involved in hospitality, restaurants, and similar then there is a special pension that automatically gets paid into every month. I don't really know the specifics because I'm not part of said pension.

The state pension is somewhere between 700 (each if in a couple) or 1100 (if single) a month. This is then supplemented by private pensions which are afaik basically required to be offered by all companies, even if they aren't created equally, and as mentioned above there are special industry or union pensions. Then add in things like socialized housing (which is much nicer than in the US or UK), and the lack of need for a car here and you can get by much more easily.