I think all the responses in this thread indicate that the posters might be expecting furniture grade wood from the DIY stores like Wickes, B&Q, etc.
It's generally not; it is construction grade material selected, cut, dried and machined to meet construction grade standards. Construction grade material is dried to just under 20% MC, not down to the 8% or 10% MC required of furniture grade wood if it is dried in Europe. There are other considerations too, such as the dimension of the log selected for construction grade material, and the species.
It is unrealistic to expect construction grade material to perform well as interior joinery or as furniture parts without additional seasoning, selection, machining, etc.
The plastic shrink wrapping seen binding wood in DIY stores is often regarded as a sign of low quality. It's not really. The plastic wrapping is a quite effective seal between wood dried to about 18%MC and the conditions experienced inside these stores where exposure to the atmospheric RH would reduce the MC quite rapidly, below acceptable construction grade standards.
If you ever watch furniture grade timber imported to the UK from the US being unloaded at the timber yard, you'll notice the large packs of closed stacked wood are almost all shrink wrapped in plastic. This helps reduce the speed of moisture regain between the US kilning operation, where the standard for furniture grade wood is 7%MC, and delivery to the ultimate users' door.
In reality, the conveniently packed pieces of wood found in DIY places are just that-- convenient. And convenience costs extra money, alot extra at DIY stores. If it is construction grade material you want, and you want to pay less, then you will find it much cheaper at a wood supplier that sells construction grade timber to the construction trade. Similarly, if you want furniture grade wood you should really go a timber merchant or supplier that sells that grade of material to the furniture trade. Slainte.