Revenue output and input methods

Hello!
I have had some issues regarding output and input methods
In one example the cost of sales is taken as “costs to date”.Like in this one

On 1 October 20X8 Pricewell entered into a contract to construct a bridge over a river.
The performance obligation will be satisfied over time. The agreed price of the bridge
is $50 million and construction was expected to be completed on 30 September 20Y0.
The $14.3 million in the trial balance is:
$000
Materials, labour and overheads 12,000
Specialist plant acquired 1 October 20X8 8,000
Payment from customer (5,700)
––––––
14,300
––––––
The sales value of the work done at 31 March 20X9 has been agreed at $22 million and
the estimated cost to complete (excluding plant depreciation) is $10 million. The
specialist plant will have no residual value at the end of the contract and should be
depreciated on a monthly basis. Pricewell recognises progress towards satisfaction of
the performance obligation on the outputs basis as determined by the agreed work to
date compared to the total contract price

Answer for this question

Progress
Work completed to date has been agreed at $22 million so the contract is
44% complete ($22m/$50m).

(iii) Statement of profit or loss
Revenue (44% × $50m) 22,000
Cost of sales: per TB 12,000
Plant depreciation (W4) 2,000
–––––– (14,000)
––––––
Profit to date 8,000

And in another example where ouput method is applied, the cost of sales is the percentage(work certified) of total costs, not costs to date

Henley Co entered into a $10 million contract to build an asset for
a customer on 1 April 20X4. The contract is expected to take 2
years and a surveyor has assessed the value of work done as $4
million. The contract will cost $8 million and Henley Co has spent
$4 million to date. Henley Co measures progress towards
completion using an output method, comparing the work certified
to date to the total contract price.
What profit should Henley Co recognise for the year ending
31 December 20X4?

Answer
$800,000 – Using the output method, the contract progress is
assessed at 40% ($4m/$10m). Therefore 40% of the revenue and
expenses should be recognised in the statement of profit or loss
during the year. This would give revenue of $4 million and cost of
sales of $3.2 million (40% of $8m), therefore giving a total profit of
$800,000.

Why dont they use costs to date as cost of sales?