Market liberalization in the nineties. It happened all over the globe in various degrees; it was the trendy thing to do. Not all of it was bad, but a lot of harm was done as well.

With postage, letters still get delivered reliably, and postal workers seem fairly paid, but the parcel market is a cluster fuck of a small number of international parcel companies (some home grown from our former national postal service) that have done exactly what economic laws permitted them to do. They are somewhat regulated and high profile, so they came up with a system where subcontractors hire the actual delivery guys and own the vans and stuff (all in the parcel company's livery of course), and the parcel company pays them for each package delivered. Gradually the pay got worse due to competition, and those subcontractors that can survive either get paid too little under increasing pressure (due to covid leading to more packages ordered), or, as happened in Belgium this year, they hire illegal aliens and underpay them.