People share a universal behavioural trait: if there are profits to be made, the effort to get that money will attract investment. This is true in the private sector, the market sector, as well as the public sector.

If politicians get money to spend and don't have to be responsible for taxation, then of course that will bias their attitude toward more spending as opposed to cutting back on spending.

Imagine that Queen Elizabeth I, in her time, had the opportunity to give out a monopoly for playing cards within the kingdom. She knew she was going to give it to one of her courtiers. These courtiers would then all try to curry her favour. Meanwhile, they would not contribute anything to the product of the kingdom, in fact, they were wasting resources trying to secure a single prize. That, more or less, is rent seeking.

If you have an area where high-income receivers concentrate, you have a higher fiscal capacity. That fiscal capacity is a valuable resource and will create rent-seeking. People will trying to get that resource one way or the other, including immigration. It is very much like the medieval peasants putting their sheep on the commons pasture. It is better than the open range, and if you let them have open access they will, in fact, put too many sheep on the pasture and waste the value that the pasture has.

Politically, sometimes you get situations where rent control will go through. It is especially true in an emergency, where there is a sudden, sharp increase in demand for housing or a cut back in supply. People will simply not allow the marketplace to allocate housing resources and so you get pressures for rent control. Once you have it, it is hard to eliminate.

How would the US be different today if people coming off the boat were greeted with a welfare check instead of a shovel?

Politics is a romantic search for the good and the true and the beautiful.