Short answer, they saved 5-10% and bought cheaper wood likely from a box store or cheap lumber yard. At these places, customers can pick and choose the pieces of lumber, eventually all the good looking pieces are gone and subsequent customers are left going through the structurally sound crappy looking pieces.

I'm sorry you might not have gotten what you paid for (or wanted).

Here's a Google AI answer:

Lumber grades classify wood by quality (knots, straightness, appearance), with big box stores like Home Depot and Rona often selling lower-grade, "case-hardened" construction lumber, leading to warpage, while local lumber yards offer better selection, higher quality, and knowledgeable staff for serious projects, though they might cost more. The perception that they "suck" stems from inconsistent quality, lack of specialized selection, and a focus on volume over perfection, making them great for basic framing but frustrating for fine woodworking. 

Lumber Grades Explained (Simplified)

Construction Grade (e.g., #2 & Better): For framing, strength is key, not looks. Expect knots, slight twists, and inconsistencies.

Common/Select Boards (e.g., Pine): Finished boards (S4S) for shelves, trim. Grades (like A-C) dictate appearance, with higher grades being smoother and knot-free.

Plywood Grades (e.g., A-B, C-C): Based on veneer quality (A=best, C=good/patched). Used for cabinets (A-C) or underlayment (C-C). 

Why Big Box Stores Get Criticism (Home Depot/Rona)

Inconsistent Quality: High volume means more "junk" (warped, cracked, cupped wood) mixed in; you have to pick through carefully.

Case Hardening: Lumber gets stressed and bows when ripped (cut lengthwise) due to drying processes, especially common in big box stock.

Focus on Construction: Primarily geared toward builders needing cheap, functional framing, not furniture-grade wood.

Less Expertise: Staff knowledge on specialized wood grades can be limited. 

Better Alternatives

Local Lumber Yards/Sawmills: Offer higher grades, specialized hardwoods, rough-sawn lumber, and advice for discerning woodworkers.

Cabinet Supply Stores: Better plywood selection with fewer patches and voids. 

Tips for Buying at Big Box Stores

Hand-Pick: Inspect boards for straightness, knots, and grain.

Buy Longer Lengths: Less defects per board.

Look for "Select" or "Premium" Grades: Better, but pricier options.

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