Here is the truth according to various AI sources which would suggest you are incorrect in your assertion that the club have dropped the ball. Planning etc are the reason the project has only just started and it has started according to the club.
Fulham FC - Riverside Stand
Planning application submitted: 1 December 2017 StadiumDB.com Fulhamfc
Planning permission granted: March 2018 (approved at a planning application hearing on 20 March 2018) StadiumDB
Note: There had been an earlier approval in 2013, but it was never implemented and the 2017 application was a revised scheme.
Liverpool - Anfield Road Stand
Planning application submitted: December 2020 Liverpool FC
Planning permission granted: 15 June 2021 by Liverpool City Council’s planning committee 4dplanning Liverpool FC
The application was originally planned for spring 2020 but was paused due to COVID-19 uncertainty.
Tottenham Hotspur Stadium
First planning application submitted: October 2009 (for a 56,000-seat stadium) Wikipedia Wikipedia
Revised planning application submitted: 2015 (for the larger 61,000-seat stadium design) Wikipedia Tottenham Hotspur
Revised plans approved: December 2015 by Haringey Council, with final approval from the Mayor of London in February 2016 Wikipedia
Crystal Palace - Main Stand
First planning application submitted: 2018 Newsroom
Revised application approved in principle: October 2022 GiveMeSport Newsroom
Final planning permission granted: 16 August 2024 by Croydon Council Newsroom Fsm-online
The project has faced significant delays due to COVID-19, land purchase negotiations with Sainsbury’s, and the need to rehouse residents of Wooderson Close.
What is more, many of those clubs were engaged in some sort of exploration of their options long before they committed to the new stands and stadiums you list. About 20/25 years ago Fulham got quite a long way down the road on a new, replacement 30,000 seater stadium. It had planning permission as I recall, but the club didn't proceed. Spurs famously wanted the Olympic stadium site to build a new ground on, and fought all the way to get it. Liverpool were going to build a new ground on Stanley Park. Very few football clubs decide to expand and then quickly get it done.
Like any building project, obtaining planning permission is just one of the balls you need to juggle. Engineering designs, logistical arrangements, legal arrangements, contractors, pricing, financing... It all needs doing. Sometimes these things are lined up before the planning application is submitted, but mostly they come afterwards, as nobody wants to spend a lot of time and money on these things before they know they have got planning permission. Sometimes, the planning application is an exercise in seeing what may be possible, but only a first step towards establishing if it is actually viable.
The biggest issue is usually the economics, of which finance is but a part. Even if the bank or the clubs owners are willing to pay the cost of a new stand or stadium, unless that loan is essentially a gift which the clubs will not be burdened with or forced to pay back, the sums simply must add up. The issue is surely that the parts of the sum are always changing, unpredictably so, and often quickly.
Viability may depend on the teams fortunes on the pitch and/or the value of our playing assets. Both are factors that are subject to sudden changes. Then there is the issue of need; as many have said, if we get relegated then we won't need a bigger capacity, and Palace are never, and probably will never be, safe from that threat.
Given it takes years to go from conceiving of these projects to actually building them, and a clubs prospects can swing wildly from one extreme to the other in weeks, its a miracle these things get built at all.
None of which explains why Parish was so bullish at the outset, and then so unforthcoming in explaining the subsequent delays. For a few years now he has somewhat avoided the question, simply saying that the project is complex and that talks with Sainsburys were tricky. Thing is, he knew all that from the start.
My own guess is that the feasibility of the project is finely balanced, and that he and/or the other board members have been torn between biting the bullet and undertaking what would be the biggest part of his long term regeneration of the club, or not doing it and avoiding the risks. If it goes well, the stand would eclipse the training ground and academy in terms of legacy, and give Palace a much better chance of competing financially with the middle part of the league. If not, it could sink the club and be a huge source of regret for decades.