After a lot of use the wheels can be a problem making it hard to move.
The doors can also be a problem when the 'locking mechanism' malfunctions meaning doors keep flying open.
The service tops often don't fit properly as these are part of aircraft equipment and do not get removed with the trolley and therefore replaced or repaired regularaly.
Many inovations have been tried over the years such as heated trollies to keep the food at serving temperature but have not always been sucessful.
Weight is a consideration firstly for manouverability by all cabin crew and catering/loading staff. Also for overall aircraft weight for fuel purposes, weight costs money!
I have seen bar trollies with built in cash draws and sales computers however purchase cost of these is a consideration for the airline along with serviceability issues
Setting up a trolley for service is pretty quick probably less than 10 minutes for bar service. Loading up for main meal service is more time consuming as you are dealing with ovens and hot inserts.
Hope this is of help and good luck
