[Note 7 Questions & Answers] beachletter:
Your thinking is understandable, but let me tell you why it is naive.

In September the first "safe" Chinese Note 7 explosion happened and the owner sent it to Samsung. Just in a few days Samsung released a statement saying that they've tested the phone already and it was heated by 'external sources'. Nothing's wrong with the phone at all, case closed. Soon Korean media was spreading news suggesting Samsung was going to sue the user for Fraud (this was not an official statement from Samsung, but somebody clearly spread it using Korean media as an intimidation tactic).

When news about the second case was spreading, Samsung released a statement saying they tested two phones and they were all heated by "external sources". But in reality Samsung only collected one phone (the owner in the second case showed evidence to media he didn't give up the phone to Samsung). Samsung later quietly modified their statement.

Owner of the second case told media that one of the first things when Samsung staff visited his home was to take pictures of his microwave and oven. After seeing this the user do not want to give up the phone to Samsung. Imagine what can you do if a company like Samsung is going to frame you to protect their sales, and you already gave the only evidence that could prove the case to them?

Still Samsung managed to settle the case with some other owners of exploding phones under the table, and they must have been in possession of multiple exploded "safe version" Note 7 back in September (counting China and HK cases, I estimate at least 5-6 units).

With China as a testing ground for US replacement units, Samsung have had plenty of time to find out what's wrong. They either:

1. Didn't do a sincere investigation, just focused on framing it as "user abuse"

or

2. Did try to investigate but were so incompetent that they still have no clue what's wrong

or

3. Did find out something's wrong but underestimated its seriousness. They decided to keep the defect a secret, and take a risk to continue the replacement program anyway.

Anyway, the owner from the fifth and sixth Chinese cases are brave (these are also people with connections and some spare cash), they decided to find a lab themselves to independently test the phone. This will cost them a lot of time and money, way more than the cost of the Note 7. This is currently in progress, CTTL lab in Beijing said they don't have enough equipment and have to send it to Shanghai for further inspection.

By the way, the fifth case owner also invited Samsung to do an industrial CT to his phone under his supervision, Samsung refused.

Now the "safe" Note 7 in the US also starts to explode. The first case (not the first exposed case on the Southwest plane, but the earliest case in KY) happens with an owner who, despite end up being hospitalized, partially cooperated with Samsung and let them X-ray the phone. The cooperation only stopped when he received a sent-by-mistake text from Samsung employee saying:

"I can try and slow him down if we think it will matter, or we just let him do what he keeps threatening to do and see if he does it."

I should add that even if he did not get this text, even if he didn't know about all the ugly things Samsung did to Chinese owners, it is still smart for him to retain the only piece of evidence. Remember he suffered serious smoke inhalation, and if the damage end up being long lasting or he felt that he deserves compensation, he will need the crucial piece of evidence to take legal action towards Samsung.

As for Samsung, they tried to hide this case from public knowledge, which resulted in no warning towards the second US case that grounded a plane.

When a billion dollar business is at risk, don't be so naive and think that some big international company will be totally honest with their mistakes and make your welfare their priority, even if it is Samsung.

Or should I say, ESPECIALLY if it is Samsung.