When I was young (I’m 32, BTW) the Jerry Lewis telethon would take up 20+ hours every Labor Day. The Easter Seals telethon was as long while numerous national (like the UNCF) and local telethons took up good chunks of air time. The only telethon I’ve seen lately is the Jerry Lewis one, and TV stations usually air only 10-12 hours. Why did they all go away? And if telethons are rare these days, why have the amounts collected by the charities gone up?
Cable and VCRs.
When all you could get was somewhere between 3 and 7 channels, one of those channels can easily replace all their programming with unending hours of telethon.
When 80something channels are competing for viewer attention, along with everything they happen to have taped and all the DVDs they can buy, stations make different choices.
Another WAG would be that telethons negatively impacted the organizations cash flow. Many donations would wait to be sent when the telethon occurred and not earlier, meaning that the orgs were likely cash-starved in the months leading up to the telethon. If you’re going to get $10 million/year, financially it’s better to make a low-key but sustained effort to get $900k/month in the organization than a one-shot infusion of $10 million every Easter. It makes for smoother planning.
More likely it was because the FCC used to consider a station’s public service programming as an important factor in judging whether to renew its license. It stopped doing so, and the amount of public service broadcasting dropped precipitously.