Anyone can take a test at a place and time of their choice. The results are stored on the server, at once and available for collation and reporting. The dramatic new technology brought by the Internet gives you distance testing on demand. Before the Internet, computerized assessment was a good thing but had problems at a distance. With the Internet, it's only a matter of time before it becomes commonplace.
Identification is an important issue in all assessment.
You need to have a reliable way of identifying a person, checking who they really are. For example, you need to stop someone from getting a friend to do their test for them. Although this isn't as common a problem in real life as it is in the movies, you do need to have confidence in who people are to give any meaning to assessment. This is the same whether the test is on paper or on computer. The situation is analagous to bank cash machines - fraud does happen, but they are still extremely useful.