compulsive shopping

could be, but you better wait for added input

I am going on memory here and would like some corroboration, but I think it is getting old small shops to close by paying compensation.

the truck system is one in which a company is forced into a deal, in a rather unequal manner. The term winkelnering can be found in Van Dale translated as truck system. Normally the truck system applies to employee/employer relationships in which a part of the wages is paid in goods rather than in cash.

A monopoly would be another term for it, i.e. "forcing" you to purchase from a single source (like Moira B's answer):

Volgens de bewindsman kunnen afspraken tussen universiteiten en boekverkopers geen kwaad. Sterker, die kunnen de studiekosten flink terugbrengen. En studenten - 'slachtoffers' van de deal - kunnen afspraken tussen instelling en boekhandel gewoon naast zich neerleggen. Gedwongen winkelnering is verboden in Nederland en van een monopolie is dus geen sprake.

ref. http://www.observant.unimaas.nl/default.asp?page=/jrg21/obs3...

Some of these methods were old fashioned and the truck system was blamed overall for the problems in the fishery. This system had federal origins. Under this system in the old days Newfoundland merchants or exporters employed the fishermen to fish for them. The fishermen did not receive money for his services, but was provided by the merchant with fishing equipment and sufficient food and necessities to keep him and his family during the year.

The use of gedwongen winkelnering doesn't really seem to be in line with its dictionary definition. As I understand it, gedwongen winkelnering is when someone is forced to buy their goods from a certain supplier (e.g. an employee who has to buy certain goods from the employer's shop).

In the case referred to in the Asker's text, the situation could be said to be the opposite: suppliers are forced by the buyers to sell at less favourable terms than they would normally wish.

The situation is actually more complex than this, however. A report was recently published by the UK's Competition Commission into the relationship between the large supermarket chains and the suppliers of fresh produce. The report found that the tactics employed by the supermarkets to exert pressure on were wide and diverse and not always scrupulous.

Here's an excerpt:
"11.26. Many suppliers commented on the purchasing power of the main parties, their ability to drive down suppliers’ prices to uneconomic levels and what they saw as their general high-handedness. A consultant to the packaging industry noted that ‘the degree and variety of pressure upon the suppliers was extremely alarming—all complied with the retailers’ demands because of the dread of de-listing’. (See paragraphs 11.48 to 11.55 for a discussion of delisting.) A small supplier commented: ‘The power of the multiples, and especially of young (c.25/28) buyers, without experience, is frightening. [They have] the power to dictate prices and margins, display or not, allocate space and threaten covertly. It’s why we would never allow more than 15 per cent of turnover to be supplied to multiples.’"

From paragraph 11 of "Supermarkets: A report on the supply of groceries from multiple stores in the United Kingdom"