What is a "Rent-Seeking Economy"? This is actually a technical economic term which any economic student would study in their university. In the simplest form, economic output (which we call GDP nowadays) is the result of the input of labour, capital and raw material. However, capital in modern days' term, is split into smaller units like funds, technology, land, and such. Whatever is produced could be termed as Value Add which could then, distributed to labour as wages, interests return for capital funding (Profits )as well as rent for land use.
Rent-Seeking behaviour may not only refer to maximizing rental return for land. It has developed into greater theory of how money was used to buy influence on government to redistribute wealth to their favor without creating new value or wealth in terms of value add via production of products and services as a whole. You may read more about Rent Seeking behaviour from Wikipedia.
Rent-seeking behaviour may include legalized monopolies which exert influence on government to provide them special treatments and concessions. The recent extortion of $2Billion for bus companies and $0.9 Billion for MRT repair are examples of rent-seeking behaviour.
What has Rent-Seeking behaviour to do with Labour Day? The following is a quote from Adam Smith:
"As soon as the land of any country has all become private property, the landlords, like all other men, love to reap where they never sowed, and demand a rent even for its natural produce. The wood of the forest, the grass of the field, and all the natural fruits of the earth, which, when land was in common, cost the labourer only the trouble of gathering them, come, even to him, to have an additional price fixed upon them. He must then pay for the licence to gather them; and must give up to the landlord a portion of what his labour either collects or produces. This portion, or, what comes to the same thing, the price of this portion, constitutes the rent of land ...."