In a typical US installation, the connection between the utility service and the dwelling service is made at the meter box. The meter forms the physical connection. When it is pulled, utility service is cut.

Secondary sources of electrical power such as solar panels, batteries, etc are connected downstream of the meter, i.e. connected to the load side from the perspective of the utility provider. Pulling the meter disconnects utility service but does not disconnect the secondary sources of electrical power. The dwelling therefore remains energized [and that's the point of installing such systems].

The difficulty in deenergizing the system presents a hazard. Finding and identifying the various disconnects takes time and is subject to error: who knows what was done for convenience or through poor planning or plain old stupidity.

Even if there is a disconnect for a grid of solar panels this only deenergizes the load side of the grid. Panels exposed to sunlight remain energized. Similarly lead acid batteries maintain an electrical potential when disconnected from the load side.

That you might not be there when you need to go to island mode or that you might not even be aware that the grid is down because you and a bunch of neighbours are capable of sourcing enough power that your 'off grid' detection mechanism fails.

There are solutions for this, it costs a little bit of money and depending on local regulations it may or may not be allowed.

So yes, you can override this and if you mechanically disconnect from the grid then you are typically allowed to operate your installation in island mode. But if you get caught backfeeding the grid when the grid is down then you will more than likely lose your hookup.

Most cheap/light inverters need an external power source to sync to and will automatically shut down if the grid is not available for synchronization purposes, which makes them compliant with the demands of the utilities. If you want to go to island mode you'll need a system that is considerably more expensive (batteries, load based inverter rather than generation capacity based) than one that can't.

It's also not a theoretical concern for disconnected panels either; my late father was consultant in a lawsuit where a small mechanical design flaw in the solar panel connector boxes combined with rough installation procedures caused farms all across France to go up in flames.

It's also not that strange considering the farms would often have 20+ panels generating multiple kVs worth of electricity. Afterwards he refused to put any panels on our home without having a proper micro-inverter installed.

that is an interesting fact! wonder if there is a simple solution like a chemical blinder, that could be integrated into something sort of like a "EPO" button, making the panel inert in terms of voltage when hit? Just like the fire rescue folks can pull a breaker or service disconnect for traditional mains?