A friend of mine is an electrician in Germany who had a lengthy discussion about this with another friend of mine who was drunkenly complaining about how large corporations pay less for electricity. I'll try my best to reconstruct what he said in response.
Residential customers use highly variable amounts of electricity and typically pay a base rate in addition to usage which can have different tiers so additional use may get cheaper if you exceed a certain threshold. Often these contracts also offer month-by-month cancellation or may include a certain period for which the price is guaranteed not to change.
Industrial customers instead often buy bulk volume commitments. Instead of paying per use, they commit to using a certain amount and pay for that exactly. They also generally have much longer running contracts. There are also contracts that directly tie the price to the daily (or in some cases even hourly) market rate, which is usually not an option for residential customers. Their energy use is also generally more predictable than the load required for residential areas with the equivalent consumption so the cost for running and maintaining the grid is lower. Additionally there is a recent trend towards DC power delivery, further cutting costs.
Rooftop solar panels and domestic EV charging actually contribute to the cost of maintaining residential grids because they add to the peak load and variance, both of which have to be compensated for. In other words, per unit of energy sold, residential customers simply have more overhead than large scale business customers.