Grunff said

Are /you/ serious? This is the standard way of hanging wall units, common
across many ranges.

Yes, it's 20 years since I fitted a kitchen so much has changed!

You're not supposed to just screw it to plasterboard - you need something
behind it.

As stated in original post, this is plaster board dry lined over brick wall!

Occupational hazard - working in heavy(ish) engineering has the disadvantage
that anything less than an M16 bolt looks positively dangerous!

Phil