On almost all aircraft used for these short routes, the FC cabin is small. There's no reason that FAs can't do a drink service under normal (non-turbulence or should we say not rough air?) conditions. If PDBs aren't being offered, orders can easily be taken before takeoff and often can also be taken even if PDBs are being offered, although I can understand the philosophy of not doing both (adult) PDBs and drinks service on such short segments.