Plaster walls in brick houses usually do have studs, they're just harder to find. You can use molly bolts for the cabinets, screw them into studs, or - if very heavy, French cleats will provide the most support. For tips on finding studs in plaster walls and hanging just about anything, check out "How to hang pictures (and other stuff) on your walls." Article also reviews different types of hangers for different types of walls etc.

There are studs there but just hard to find . IMO this is why Ikea always uses the hanging rail it works on all sorts of walls and in Europe many are plaster .The rail works like the french cleat in a way it spreads the load over a wide area and the hope is at least some of the screws hit studs.

French Cleat.

Finding studs in plaster walls = magnets to find the nail heads.

A youtube video on plaster walls for starters.

https://www.google.com/url?q=https://m.youtube.com/watch%3Fv%3DlkkaLHo5ZMM&sa=U&ved=0ahUKEwifrfnLsfrgAhXDjVkKHVojBW0QtwIICzAA&usg=AOvVaw2ujOc-SLH9ptDS8xvfYuCv

I would assume you have something solid behind the plaster. Magnets never worked for me. The only reliable method I've found is to just keep drilling holes in a line until they hit a stud.