Are there structural differences between the various A319 MTOWs, eg beefed-up landing gear, or is it just a documentation issue, principally to get lower landing fees based on MTOW ? Obviously the Air Canada A319s that operate Heathrow to St Johns, Newfoundland, well over the distances being quotes here, westbound against the prevailing wind, and with no opportunity for a fuel stop, are perfectly OK.
Another issue can be the commercial team selling significant air freight loads, something that the charter carriers tend not to do as much, for example substantial loads of agricultural products inbound from places like Cyprus to the UK. Leaving pax bags off, as described above, with all the timewasting and gross disruption to life for the pax when this happens, just because the carrier has not got a grip on the capabilities of their aircraft, is unacceptable, and the regulators should identify this and deal with it.