According to High Guard, common areas have laundry and it’s not uncommon for staterooms to have food preparation units (possibly autochefs from CSC)
“High Guard p.37” said:
ACCOMMODATIONS
Most ships utilise the humble stateroom, but other types of accommodation are possible. All accommodations listed in this book other than low berths and acceleration benches include a fresher, while all staterooms and barracks include a small food preparation unit. Laundry facilities are usually located in a common area.
So, at least smaller ships, might not even need a dedicated kitchen, and a washing machine can surely fit in a corner of the common room.
Also, the chairs and tables drawn on deckplans are rarely indicative of exact furniture placements. They’re rather icons that easily tell the reader that “this is common area”. The actual contents of the area could easily include a laundry corner, food prep area, dining tables and so on. Interior partition walls can be added as needed.
The element cruiser box set deckplans doesn’t even have “common area” designated on the plans. Instead, they’re split into galley, lounge/bar, gym, theatre and so on, so there are official examples of common areas not just being a large room with lounge chairs in it.
A smaller ship might not have enough common area to split it into various sub-units, but assign one part of the room for furniture storage and the room can easily be reconfigured at need (futuristic smart furniture surely helps too!).
Regarding storage, what’s to say an entire wall of the passenger common area isn’t devoted to storage lockers? Just because they can’t be seen doesn’t necessarily mean they aren’t there.
The naval campaign sourcebook (part of the Element box set) expands upon this by introducing a concept called “supply units”:
“naval campaign sourcebook said:
Stores, spares and supplies are abstracted as Supply Units, or SU. A starship is assumed to carry enough spares lockers, spud bunkers, and other stowage for its normal level of supplies without needing to use cargo space for the purpose. Note that supplies are separate from expendable large ordnance such as missiles or fuel for the power plant and jump drives, and represents food for the crew as well as replacement parts for the ship.
Looking at the Element class blueprints, there are rooms labeled storage as well as lockers in some corridors.