I've seen power cord fraying problems on laptop AC adapters from Dell, HP/CPQ, Apple, IBM/Lenovo, Toshiba, and Sony, and those are the ones I can think of off the top of my head. I've also seen it on AC adapters for Wi-Fi routers, modems (phone, DSL, and cable), ink-jet printers, routers/firewalls, cell-phones, etc. from dozens of manufacturers. This is an industry-wide issue, not anything specific to Apple, and I can't say it's significantly more likely on any one brand.
In 15 years of owing Mac laptops none of my Apple AC adapters have ever frayed or failed. One was recalled and replaced due to a potential fire hazard (not fraying related). MagSafe is the best laptop power connection yet put on the market, but like virtually every other adapter for portable devices, the thin DC cord is subject to fraying if you routinely stress it.