One of the Swiss mobile phone operators has just changed its scheme for recharging its pre-paid cards.
In the old scheme, customers had to purchase recharge cards. These cards were offered with the following amounts, 30, 50, 80 and 100 CHF.
With the new scheme, there are no cards anymore. Customers simply give their mobile phone number and pay for the amount they want to recharge. Surprisingly, you can only recharge with the same fixed amount as before, that is, 30, 50, 80 and 100 CHF.
It is understandable that as long as you need to manufacture recharge cards, you have to specify fixed amounts such as the ones fixed by the operator. But if you remove the cards and ask customers to simply give their phone number than why shoudln't they specify any amount they wish, 17.50 for example?
It appears that the recharging service has been re-engineered only partly. The norm that specifies the fixed recharging amounts was not challenged. Maybe because it looks so "normal" to have fixed amounts that people don't even think of changing it.
If you want to consider other examples, think of Adobe Acrobat. Reading a Actobat document is made difficult by (among other things) the representation of a paper page on screen. When you scroll through the document, you need to move from one page to another even though this is a screen not real paper. The norms of real paper have been transferred to the screen. MS-Word is better by comparison because it offers a way of folding the separation between pages without removing it completely.