Selenium sometimes selects the incorrect page feature

I am attempting to scrape the prices of various items of produce from UK supermarket websites. On the Asda website, I occasionally get the correct value, and occasionally the incorrect value.

I believe that there is more than one instance of the class I am searching for on the page (called co-product__price-per-uom). There is the main instance, the one I'm looking for, but there are also links to other items on the website with different values. It seems like sometimes these other items are being loaded first, and selenium is picking them up, rather than the main one I want.

Here is my code.

price_raw = WebDriverWait(browser, 10).until(EC.presence_of_element_located((By.CLASS_NAME, str(class_list[url_list.index(url)]))))
            price_raw = str(price_raw.text)

Can I ask Selenium to wait until all elements on the page are loaded, get all the ones that have the name value and then just take, say, the first in the list? Will the list order be the same every time or will they be added to the list as they are loaded?
Thanks

You were correct in that there are multiple products on the page that all have the class you were looking for. The easiest way to narrow it down to the one you want is to use the dev console. In Chrome, press F12 to open the dev tools and then press ESC to open the console. In the console use $$() to test CSS selectors and $x() to test XPaths. In your case run $$(.co-product__price-per-uom) and see that there are 4 elements that match that locator. Expand the element list and then hover over each one until the desired element is found. From there, look up the DOM until another element that can be uniquely identified is found that can be used to differentiate the element you want from the others. There are many such elements but I used

<div class="pdp-main-details__price-and-uom">

Add that to your existing CSS selector and get

.pdp-main-details__price-and-uom .co-product__price-per-uom

which locates only the desired element.

If you are interacting with an element on the page, you want to wait for clickable if you are clicking and visible for just about anything else to prevent exceptions being thrown. Presence just means it's in the DOM but not necessarily visible or clickable, etc. Updating your code,

price_raw = WebDriverWait(browser, 10).until(EC.visibility_of_element_located((By.CSS_SELECTOR, ".pdp-main-details__price-and-uom .co-product__price-per-uom"))).text