I work at a UK regional airport and a couple airlines who offer us jump seat rides but others either make it so beaurocratic and/or that we still have to pay passenger taxes, that it's not worth it.
The management at Flybe have made it very difficult or nearly impossible to get jump seat rides, (all we wanted was round trips without disembarking).
At first they told us that the throughput of very inexperienced first officers made it impracticle to have flight deck visitors and that's completely understandable, but that was nearly three years ago.
Others prioritise their own staff, again, if it's pilots etc then it's perfectly understandable, but I'd wager that there's more to be gained by ATCOs being on the flight deck for 2 -3 hours on a round trip than cabin crew or ground staff.