Doesn't seem that long ago since I was last there.Bu**ers have changed the free drop off collection point. The old free drop off collection is now £2 a short visit and they have moved the free one to what they say is a 5 to 10 minute walk from terminal Signposted Drop Off 2. Turn right at last roundabout instead of left into airport. Not signposted as free as you can imagine.
They have monopolised it very well with double yellows on all the approach roads and big warning signs with fines about stopping to drop off or pick up on them.
What do taxis do --are they charging customers £2 extra?
Daughter and boyfriend fit enough so they can walk.

And its a bit of a lonely walk at night in not the most secure looking area and with very little shelter if its slashing down.

The yellow lines you mentioned are red,if you stop on them even for just a few seconds the camera van based on the roundabout will snap you and a fine lands on your doorstep, they start front Dunlop road which is the turning on the left just after the premier inn. A lot of people including myself park here instead of the airport car parks whilst waiting to pick up family from incoming flights. The locals a r e in the process of arguing with the airport(peel holdings) to relax or review the parking charges. Taxis get charged £2.50 everytime they pull up at airport and so pass this charge onto the customer.
An alternative would be to purchase a all day all areas walrus card, you can buy them in the airport, get the bus to south parkway jump the train into town and change for the Wirral line.

News story from when they introduced it in 2014:

http://www.liverpoolecho.co.uk/news/liverpool-news/liverpool-john-lennon-airport-axes-7120871

save the planet and stop flying. Or stop using Liverpool airport. Use Manchester and spend more money on petrol. The choice is yours.