Not all use wood, but there are problems with foam core as well, if there is an air void and the resin content lamintaing the core and glass together is not enough, the glass will slap the core and cause it to turn to dust inside causing bigger issues. Some builders use foam or balsa core to lighten a boat up, that is great if you want high speeds, but light boats typically get beat up a lot more in rougher seas as well so it is all a trade off, oh and the foam or balsa core costs more, wood can be done in house, most balsa or foam core is cut out of house and brough in in kits and placed in the mold like a puzzle. Kevlar hulls are another option, but they are more expensive and you need a kilm to cook them to harden to strength, if a step was forgetten or not enough of each material used the strength can be significantly compromised. Wood has its down sides, but really is the easiest to use and most proven, balsa and foam cores are catching up and getting better, but for a transom they lack yet. Grady did not cut corners, moreso, owners are not well informed of how to maintain their boats, and the ones that do, half just do not care knowing they will not own the boat long enough to see the issue and let the next owner inherit the issue. The trim on the transom is not fiberglassed, but almost no builders with an open transom or euro transom do this, your talking about a LOT of man hours of work to get it level and flush and it is hard to work from inside the hull in this area once the deck is laid inside the hull. The problem is not with the build technique, but with owners not checking to see if screws are tight or to know that when the metal trim pits it is now in need or being replaced, better yet, it should have been polished and waxed and then washed after each trip to keep salt off and prevent the corrosion all together. These problems are not with just Grady's, I can go through builder after builder with issues, some are from the manufacturing of a poor product others from poor maintanance from owners. Another issue is with transom mount transducers, too many owners just tap them with screws, did not drill into the glass backwards first...this is a must or you WILL crack they gelcoat exposing the glass to water and then seepage. Some do not properly seal screws or bolts when adding equipment. anything below the waterline needs 5200, 4200 is ok, but 5200 is best and YES it CAN be removed...use acetone and some elbow grease and it will come off. If gelcoat ever cracks in an area it will get wet repeatidly it needs to be resealed, gelcoat repair kits are fairly easy to use and fairly cheap, Grady sells one that matched almost perfect from their dealers. Ignoring these cracks will allow them to spread and cause water seepage when spending maybe $25 would have fixed the problem as well as made the boat look nicer.
As far as the bayliner comment hahahahahaha I'm going to laugh at that that was just rediculous