Many of the less well off and towards the fringes of society may be criminalised for the simple act of license fee evasion and this can escalate to more serious penalties quite quickly. This is complicated by the advent of video by broadband and people can easily fall foul of the rules inadvertently.
The cost of collection is prohibitive in our reduced, post Labour, state. Why have a separate system for something whereby 99% of country use the service? And then a separate and complicated system of letting people have licenses for free if they cannot afford one such as that for OAP's. If ever a tax should be bundled in with income tax or such like to save costs I don't know.
The only arguments I have heard in favour of a separate license fee are so that the cost is linked to the service and that it implies BBC independence from government. These are easy to refute: the first is that there are very few public services where the user pays the exact price, why so for television? And for the second, the government sets the amount of the TV license fee, so the 'independence' tag is somewhat of a charade.
Finally, from a libertarian viewpoint, the mere perception this engenders when viewing constant advertisements on the TV telling us we are being watched and there is a database on us all to cover this silly tax, with vans roaming the country prying into our watching habits does not add to one of a free and liberal country.