The Corrosion of Cybertron was an event that took place over a few centuries, but was only recognized as the disaster it had become about 700 years ago - when people started falling through the rusted outer layer of the planet.
This, of course, wasn't supposed to happen. Municipalities were supposed to hire private contractors to maintain their areas of the planet and replace any failing planetary panels as they were detected. Alas, this is Victorious Decepticons, not some nation where it's illegal to do things like collude with politicians to gain contracts...and then never do the actual work. So, being Decepticons, that's what happened. Everywhere. With every contract.
The end result was that even though plenty of municipal funding was spent on "infrastructure contracts," no actual infrastructure maintenance was happening. Worse, most of the people blithely assumed that shoddy work was being done rather than none at all, so it was generally believed that Cybertron's outer layer was actually in decent shape underneath the rust coat.
It wasn't.
One day, Leader Megatron was walking through the streets of the capital, rust crunching underneath his feet, when he fell right through the first layer of the planet. Since Cybertron is actually made of several layers of metal, arranged somewhat like an onion, the core of the world wasn't the next stop. He landed rather harshly on the second layer 1000 feet below, braking his fall with his foot-jets well enough to avoid damage but not so well as to have a soft landing.
Infrastructure maintenance was nationalized the second the leader propelled himself back to the surface and got to his broadcasting room to make the decree. He also used the occasion to ram through an omnibus package that reformed Debugging, fire control, and other essential services at the same time - though to this day, Leader Megatron insists that the changes were not "reforms" and were CERTAINLY not "anti-corruption measures," but instead, merely "efficiency improvements." This is because the Decepticon Government is seen as having one main duty: To protect the ability for Decepticons to operate as Decepticons, which is to say, corruptly. The leader had to be extremely careful in how he applied even the slightest bit of brakes.
The Corrosion of Cybertron ended up costing 100 trillion Cubes of Energon, 10 million bot-hours of labor by government laborers, and 500 million tons of planetary steel to properly repair all of the corroded areas. Though the Raid Tax was put into effect along with the reforms, most of the cost was borne by Leader Megatron himself through the vaults of Megatron Energon, and of course, in the form of steel from Megatron Metals - the only company big enough to supply that much metal.
Now, 700 years later, infrastructure maintenance and other essential services remain nationalized, and are performed by employees hired directly by the government. Sub-contractors in these industries no longer exist. Good ongoing maintenance has ensured that Cybertron remains not only physically stable, but nice and new-looking as well.
. 